FOR AMERICANS thinking about learning a language—and to lesser extent, for Europeans and Asians—the name Rosetta Stone may come to mind. In America in particular, the bright-yellow brand is, if not quite ubiquitous, to be found wherever the internationally-minded are: railway stations, airports, the ad pages of newspapers and magazines. This week, I wrote about the business of language learning, also looking at Berlitz, for the print edition.

As a language writer, I’m often asked "Should I get Rosetta Stone?" For years, I was sceptical. In 2005, I reviewed an earlier version of the software, and came away partly impressed and partly frustrated. The interface was clever, and I truly seemed to be learning my test language with little conscious effort. But before long, I found what I thought was a near-fatal flaw: that Rosetta Stone barely differed at all between languages.

Arabic and Swedish pose very different challenges to the learner. One example: an early Rosetta Stone lesson teaches the difference between "he walks" (singular) and "they walk" (plural). But the Arabic version I looked at would occasionally show a man and a woman with the word yamshiaan, "they [two] walk." The dual is distinctive to Arabic and a few other languages. But Rosetta Stone did not single out and teach the dual separately. The learner was just supposed to figure out that when there were two people, the ending would change from –oon to –aan. The software should have singled it out for explicit practice.

Fortunately, Rosetta Stone agreed. Between Version 2 (which I had tested) and Version 3, customisation was added for each language. The peculiar difficulties of each language would get more focus, even while the basic lessons stayed the same.

So what does today’s top-end version, Version 4 TOTALe, look like? I spent several months with the software, working on Mandarin. (I tested Mandarin using Pinyin romanisation only. The software lets you learn with Chinese characters, but is not really designed to teach this unique and difficult system. Rosetta Stone focuses on getting you to speak.) The short verdict, after many hours spent: though it still has shortcomings, Rosetta Stone has come a long way, and I think it is a genuinely useful tool for language-learning.

Those who don’t know how Rosetta Stone works are encouraged to try the demo. But to describe in a few words: Rosetta Stone does not use your native language. It uses only pictures and words in the target language. First, the learner gets a few nouns: a man, a woman, a car, a bicycle. You hear the word, see the word written and see the picture at the same time. Soon you start practicing them: you see the picture of the bicycle and have to click on one of four words, only one of which is zìxíngchē, bicycle. Or you’ll see and hear zìxíngchē,and have to pick which of four pictures has a bicycle in it.

Soon, you move to pairs: a boy and a girl, a man and a boy, a boy and a bicycle. Then basic verbs: the man eats. The boy eats. The girl eats. Gradually, things get more complex: the girl drinks juice, the girl drinks water, the man reads a newspaper. All of this builds block by block. The learner is solving the language like a puzzle. Only one new element appears at a time. If you see, in Mandarin, the man is reading a [unfamiliar word], you will have already learned "The man is reading…" and the picture will make clear that the new wordis "book". Then you get to the book is [unfamiliar word] the chair, with the book on the chair. So the new word is on. In theory, you should never struggle too hard to figure out what’s going on.

In theory. Now we must get into practice a bit, and into Mandarin, to see where this is not always the case. Take he is eating. In Mandarin, this is four short syllables: tā zài chī fàn. But what do they mean? Tā is both "he" and "she". So the rest is "is eating" … right? Not quite. You have to do some digging outside of Rosetta Stone to figure out what’s going on.

Zài is a particle that goes with verbs denoting an ongoing action. Chī is the verb "eat" itself. But what’s fàn? It’s "cooked rice", of course. Rosetta Stone won’t tell you, but chī is transitive only. It must have a direct object in Mandarin, and so a dummy object (cooked rice) has to be supplied. The man might really be eating steak, but you say he's eating cooked rice, if you just want to say he is eating and don't know or care what.

At first, you may just learn chīfàn as one unit meaning “eat”. This wouldn’t exactly be wrong. But along comes another wrinkle: when Rosetta Stone’s dog is eating, you get zhè zhī gŏu zài chī dōng xi, "This dog chī dōng xi". Why not chī fàn? If you’re clever (remember, you don’t know fàn is "cooked rice") you’ll just figure out that dogs just have a different verb, chī dōng xi instead of chī fàn. But what on earth is dōng xi? You can do some internet digging to discover that the two Chinese characters mean east and west, but that will only confuse you more. Finally, you discover that dōng xi just means "something". People eat one dummy object ("cooked rice") and dogs another ("a thing").

So Rosetta Stone is full of puzzles. Some are explicit, and cleverly designed into Rosetta Stone (like how to figure out on from the picture of the book and the chair that you already know). But others are accidental: they are a product of the fact that the program is mostly built around a common set of thousands of pictures. Each set has a man eating, a woman eating, a dog eating, and a boy eating. This is unproblematic in some languages: The man eats and The dog eats don’t require different verbs in Spanish or English. But they do in German and Mandarin, and the learner is stuck with this unintended and distracting minor puzzle.

Another amusing puzzle, among a few I could name, was why the Western-looking characters address each other as qióng sī tài tai and the like. Who or what is a qióng sī tài tai? Google will tell you that tài tai is "Mrs" or "wife". And qióng sī? It's a sinification of "Jones"! Westerners do have to render their names into Chinese sounds (and characters) if they deal extensively with Chinese people in Chinese. This usually requires some pretty extensive phonetic contortions. Again, this is fascinating, and teachable—but not explicity taught by Rosetta Stone.

Perhaps the most persistent little puzzle in Rosetta Stone Mandarin is the presence of indispensable yet inscrutable little words all over the place. Right in the first lesson, we see "a man": yī ge nán rén, literally one ge male person. "A woman": yī ge nǔ rén, one ge female person. "A dog": yī zhī gŏu, one zhī dog. And so on. What are these little words between "one" and the nouns?

They're called classifiers (or measure words), and they must be learned with every single Mandarin noun. In English we say three head of cattle or five loaves of bread. In Mandarin, every noun has a word like head or loaf that is used whenever you use a number, or words like "this" and "that": this ge man, four zhī dogs. Classifiers are inescapable in Mandarin. Some, like ge, are frequent. Some, like tiáo, have properties in common (belts, rivers and roads are all tiáo—long, and thin). But many are not obvious or easy to learn. Any sensibly designed Mandarin course will drill students in classifiers extensively.

Rosetta Stone, to its credit, does a bit. Beginning early in the lessons, and recurring occasionally, are sessions designed to reinforce the classifiers. But never is the student explicitly told what’s going on, as in the two paragraphs above. It’s simply something you have to figure out and learn to deal with. If you’re good at this kind of thing—if cracking brain-teasers in the Sunday paper is your idea of fun—you might well enjoy the challenge. In the specific case of Mandarin classifiers, though, even more explicit drilling would be welcome. Once you do figure out what classifiers are, there's still a lot of work to be done learning them all.

Tones make up another nut that is harder to crack than it should be in Rosetta Stone. Mandarin is tonal. Shí, with a rising pitch, means ten. Shì, with a falling one, means is or are. (And many other things: Mandarin has many homophones.) Western learners will usually not know a tonal language when they start Rosetta Stone. Unless they’ve done some research, they may not know to look out for tones at all. If they don't, they could do a lot of learning before realising that tone is crucial in Chinese, and will have failed to learn the tones in a lot of early vocabulary. And while Rosetta Stone tests your pronunciation—requiring you to repeat words and phrases—the software does not notice when you get the tones wrong. (I tested it by intentionally repeating the "right" syllables with the wrong tones. Even with the difficultly level set at the highest it will go, Rosetta Stone counted my replies as 100% correct.)

Again, clever or diligent learners might figure out tones early and adapt to them. But most learners could use explicit instruction. Tones are hard. Rosetta Stone is marketed as software that will teach you near miraculously, without all those annoying books and drills. But there are many pitfalls for the learner of a language, especially one distant from one’s own: foreign concepts ("cooked rice" as a stand-in object for eating almost anything), foreign grammar (those classifiers), and foreign phonology (tones) all throw up challenges ranging from mild to fearsome. Hitting them with both Rosetta Stone’s intuitive software and a traditional lesson book (Living Language makes some good ones) is far preferable to relying on Rosetta Stone alone.

Finally, Rosetta Stone has added many bits and bobs to successive versions of the software. These include solo games, games you can play with others online, and chatrooms. I found the chatroom for Mandarin mostly empty, with users often showing up, asking a question, finding it unanswered and leaving. Interactions are few. (There is more going on in the German chatroom I also visited.) But the games were a good way to practice vocabulary while having a bit of fun.

And by far the best feature Rosetta Stone has added is the opportunity for live video tuition, called Studio. With the provided headset, users can join live 30-minute and hour-long lessons with no more than a few other users. The tutor carefully guides the students (all at the same point in their learning) through a scripted session that will focus carefully on the grammar and vocabulary they're learning just then. In my first session, still fairly early on, the picture was of a family at a dinner table. The teacher asked "What’s this?" "A family." "Who is this?" (She puts a cursor over the boy.) "This is a boy." "What is the boy doing?" "He is eating." "Do you have a family?" "Yes, I have a family." "Do you have children?" Et cetera. A mistake will gently be corrected (including mistaken tones and classifiers). The learners’ native language is never used, though the teacher will occasionally type things on the screen and use clever graphical devices to explain. For example, when she said “Now you ask me,” I didn’t understand her, so she typed my name, and drew an arrow to her name.

At the moment, Studio sessions are free and unlimited with the yearly subscription, which is going for $239, and gives access to all five levels of Mandarin. (Update: the subscription now offers two Studio sessions per month for each Unit. There are 20 total Units.) Right now, the $399 five-level CD-ROM package comes with only a three-month trial of Studio. Subscribing (even though it means you don’t own the software) seems the better deal, since Studio fills a critical need for the learner: live practice with a human being. Also, a regular learner (spending several hours a week) can probably complete all five levels in a year, and save $160 while getting Studio in the bargain.

In addition, Rosetta Stone has put a lot of work into good smartphone and tablet apps. The iPhone app, miniaturised as it must be, does not keep track of my progress, and does not offer the Studio lessons, but is good for vocabulary practice while killing time almost anywhere. The iPad app seems to have all the features of the full computer software, and so allows seamless continuation of your progress away from your desk (as long as you have an internet connection). Both phone and tablet apps are free with the subscription. Users get just a three-month trial of the apps with the CD-ROM purchase.

Why? Rosetta Stone is trying to move people to subscriptions, not CD-ROMS. Their head of public relations, Jonathan Mudd, calls the software "classroom quality at disruptive pricing". They want you to think of it as a high-end ongoing service (competitive with your local language school) at a good price, not as an expensive piece of software.

In summary, Rosetta Stone has come a long way. It still has shortcomings, but so will any methodology. Fortunately, these can be mitigated if you disregard Rosetta Stone's promise of effortless learning without the need for any explicit teaching. For an adult learner, those pesky books can be a huge help when running into a dog eating dōng xi or a westerner named qióng sī. Rosetta Stone can be a great tool—alongside books, rather than instead of them.