As of now, I’ve been carrying the Samsung Galaxy Tab for a month, using it every day; this has included two major road trips. I suppose there are a few other humans who’ve had this much hands-on with a 7" form-factor tablet, but I don’t know of any others with a blog and a free hand to write what they think.

My experience with an iPad is much less, but non-zero. Also, anyone who hangs out in cafés in Pacific time and scores upgrades on a few international flights has lots of chances for iPad field observation. (Early finding: On airplanes, iPads are used for reading magazines and playing lightweight games.)

Meta · I consider both the iPad (by general agreement) and the Tab (by personal experience) good products. Thus, the world now contains one good instance each of a 10" and a 7" tablet, and it’s reasonable to start drawing conclusions as their strengths and weaknesses.

I’m going to throw the term “tablet” around pretty freely without bothering to define it. It’s obvious to me that the iPad and Tab qualify, while the iPhone and its direct Android competitors don’t. I haven’t ever touched a Dell Streak.

Finally, by way of disclosure: I’m an Android partisan by choice and professionally. But I think this discussion is independent of Apple/Android issues.

1. Pocket Phones Aren’t Going Away · Size matters. fitting into any pocket, being operable with one hand, and presenting no perceptible burden; these are hugely important features. Thus, while tablets are seductive, the chance of them crowding out the standard phone form factor is approximately zero. Here are some more reasons:

Holding a phone to the side of your head works very well for the common case where you want neither to walk around with an earphone, nor to share both sides of a conversation with the room.

A pocket phone is the right size for use as a camera.

I got totally lost in the wrong part of Copenhagan, I mean really the wrong part, and felt kind of nervous about unpocketing the Tab to find my way out of it; there’s a discretion factor that favors small devices.

2. Pocket Creep · I’m increasingly convinced that the common 3.5"-or-so form factor, as in the iPhones and the Nexus One, is unnecessarily small. While I totally love the high pixel density of both those devices, I think that the extra real estate offered by current products like the new Droids, HTCs and Samsungs trumps that.

Based on my hands-on with Evos and Droid X’s, even a little unsqueezing of web pages and emails really makes a big difference. This is particularly true when you’ve gotten used a tablet; your phone display starts to feel cruelly small and stupid.

I’d be surprised if the iPhone form factor didn’t start to creep up a bit next year. Where does it stop? Might the standard pocket phone of the future look like the Dell Streak?

3. For Sharing, 10" · A really common use for a tablet is sharing: passing it back and forth along the sofa or across the table while you give a pitch or giggle at a funny picture or take turns at a game. For this kind of thing, bigger is better, and I think the iPad form factor hits a major sweet spot.

Having said that, I’ve been demoing like a demon on the Tab these last few weeks, and it’s not bad at all.

4. For Sustained Use, 7" · On those occasions when I’ve used an iPad for more than a few minutes (once on a 2½-hour plane flight, and once watching a ball game on TV) I found it started to wear on my wrists pretty soon; I was switching it around, balancing it on this & that, and really having a hard time getting comfy.

On the 7" Tab, I’ve read 4½ books and watched a few movies and played lots of games, one way or another using it continuously on a couple of major transcontinental flights. Yes, your wrist gets tired, but you’re only using one at a time; switching back and forth is easy and natural.

5. No Bigger · There’s a bit of history repeating itself here. In the early days of printed books, the Folio format was popular, which resulted in books that were 15" tall, which is to say immense by modern standards. As history moved on, standard book sizes moved down through the quarto and octavo; today’s drugstore-paperback form factor has been stable for a while and may represent the end of this trend.

There’s a similar story in the world of photography. Its early days featured view and large-format cameras; the world of film (except for professional magazine/poster photographers) stabilized at 35mm; there’s a nice visual summary over in the Wikimedia Commons.

This trend, where the first instance of a media format is the biggest, may not be that linear in tablets; but it seems unlikely to me that there’ll ever be one that’s commercially successful and larger than the iPad.

6. Battery Life · Evidence seems to suggest that tablet designers have an easier time of it packing in enough battery capacity to remove this as a day-to-day issue. The iPad is famous for battery life, and I’ve found the Tab very good too. The day of GDD Tokyo I spent literally hours demoing with it, letting strangers install and try out all sorts of apps, and play games. By the end of our late dinner, the battery was down to a sliver, but the Tab (just) made it to bedtime.

This matters, because what I hear is battery designers are up against the basic physics and nobody’s expecting any big breakthroughs. Apple has been maybe the best at battery engineering and I frankly don’t expect anybody to improve that much on the current state of the art in the near future.

7. As Cameras · Tablets suck. I feel like a complete idiot brandishing these things at startled potential subjects. They need to have cameras, for augmented-reality and a few other kinds of apps, but when you say “cameraphone” you’re talking about something that fits in a jeans pocket.

8. Creativity · I was one of those who, when the iPad arrived, dissed it as a consume-only platform, saying: For creative people, this device is nothing.

Clearly, I was at least partially wrong. There are now successful drawing and painting apps, good enough to get on magazine covers. I’ve also read pieces by bloggers I respect, saying they were able to write this or that on their iPad.

Also, it occurs to me that a touch interface might be just fine for photo-editing in a tool like Lightroom; and see Ctein’s take on using it as a Photoshop ancillary (iPad fans should really follow that link).

What I haven’t heard seriously proposed is any tablet as a serious writing or programming platform. I’m not saying that a touch interface can’t equal a physical keyboard for professional-grade text wrangling, but I bet it’s going to take a while to catch up with the literally centuries worth of iterative refinement that’s gone into keyboard technology.

Of course, there are always outboard keyboards, but if you have to lug one of those around you might find a laptop more convenient.

9. Aspect Ratio · The iPad has a lot more screen space than the Tab, but the 1.707 aspect ratio of the Tab’s 1024x600 screen is a lot closer to the 1.778 of movie-standard 16x9 than the 1024x768 of the iPad. So for high-production-value movies, the iPad doesn’t get much use out of those extra pixels; and I can testify that the Tab is just fine for watching them.

The iPad’s screen is physically larger, which is nice for movies; thus the pixel density is lower, but that doesn’t seem to hurt. So I’d be really unsurprised to see someone make a tablet about as tall as an iPad, but narrower.

10. Games · I haven’t played any on an iPad, but I have to say that the 7" Tab feels brilliant, because the screen is pretty big and you can so easily hold it on hand and bang away at it with the other. Tilt/shake controls are excellent, but I’ve never played a really compelling game that didn’t require some control-tapping.

I really must spend some quality time with Fruit Ninja or Need for Speed on an iPad so I can come back and add to this section.

What You Gonna Do? · Seriously, will you end up with a handy little no-fuss pocket phone and a 7" tablet for books and email and games and a 10" big-screen for sales calls and family time? I’m sure some people will.

It’s way too early to be making any large-scale predictions. My guesses are that everyone will probably still have a pocket phone, that the 7" form factor might hit a real middle-of-the-road personal-device sweet spot, and that the big tablets will find lots of friendly niches.

So how does that translate into sales? I haven’t the faintest idea.