When Apple introduced iPhoto in 2002, it was a tremendous boon to casual photographers. Rather than focusing on tweaking individual photos to perfection, it was centered on easy organizing of the many images people were beginning to accumulate via digital cameras.

But as a tidal wave of photos arrived from smartphones in recent years, the iPhoto software became overwhelmed. It was often slow to scroll through thousands of pictures, and its minimal editing tools seemed increasingly inadequate.

Now, at last, Apple has replaced iPhoto with a new, free Mac app called simply Photos. It’s much faster, less cluttered and has more editing options, yet still makes them simple to use. It’s essentially a Mac app that catches up to the superior look and feel of the Photos apps on the iPhone and iPad, but with greater power.

At the same time, Apple has introduced an optional service, called iCloud Photo Library, which stores all your photos in the cloud and syncs them among all your Apple devices.

Both have been in beta, or test releases, but became available to everyone last week as part of Mac OS X Yosemite 10.10.3.

I’ve been testing the new Photos app on two different Macs, and I consider it a big improvement over iPhoto. It’s faster, easier to use and has a more modern feel.

And although the new Photos software can be used without the cloud service, I’ve been testing that, too, roping an iPhone and two iPads into the process. That’s because Apple says the two photo products are closely “intertwined.”

Alas, my positive feelings about Photos on the Mac didn’t extend to iCloud Photo Library. While syncing my locally stored photo library, the cloud service failed to do its job properly.

Even though my iPhoto library of 18,000 images isn’t considered large by Apple standards, and my home Internet is speedy in both directions, my library took nearly three days and nights to upload to the cloud — far longer than Apple estimated. And even that was only possible because I asked Apple about it for this review, and the company (with my permission) analyzed my library and found a “rare bug” it says it had never seen before. This was resolved with a back-end workaround, but I can’t consider this a full solution.

Photos

Apple had three main goals in designing the replacement for iPhoto: Greater speed, less clutter and somewhat more sophisticated editing. In my opinion, it achieved all three.

Setup was easy on both of my test Macs. The new Photos app imported my existing iPhoto libraries quickly and accurately (which is different from syncing them to the cloud).

Scrolling — even through 18,000 images — is fast and fluid. And search is more sophisticated. In my search tests — “Steve Jobs,” “Beijing” and “wedding” — I was quickly able to narrow things down by date, name, location and more.

As for clutter: While iPhoto started out as a simple program 13 years ago, over time it acquired so many options and controls that it became complex. The new Photos sweeps that all away, while retaining major features.

The main screen of Photos has a toolbar with just four big buttons: Photos, Shared, Albums and Projects. These are similar to the icons across the bottom of the screen in the iPhone and iPad Photos app.

The exception is the Projects button, which brings up things like paper books and cards, as well as slideshows. Albums also has a new feature: It automatically creates special albums for things like slow-motion or time-lapse videos you may have taken with your iPhone.

But most people will spend their time in the Photos section of the app, which is divided into the same three views you see on your iPhone or iPad. One, called Moments, gathers photos taken at the same time and place — for example, a museum you visited on a given day during vacation. The next, called Collections, is broader. It might, for instance, contain the entire vacation. The last is Years, which is just what it sounds like.

These are all meant to make it easier to find photos in large libraries. For instance, even in Years view, which features thousands of tiny thumbnails, you can simply hold down the touchpad and scroll to see larger views of each image, and then stop pressing down to enlarge it to full size.

And full size in Photos is larger and more pleasing, surrounded by fewer distractions, than it was in iPhoto.

In general, I loved the speed and ease of the new, simpler controls in Photos.

I don’t do much editing, but in my tests, it was easier in Photos than in iPhoto. Apple stresses that editing isn’t meant to be the main purpose of Photos, but the company has worked to add some options.

The finest editing controls appear first in simple formats, with sliders for things like “Light.” But you can click to expose more, such as highlights and shadows, each with its own sliders. You can also white-balance photos.

My personal favorite was a new one called Auto Crop, which not only resizes a photo, but straightens it and tries to make it look more professional — all in one click. In a shot of my daughter-in-law, Auto Crop made it so her image filled more of the frame. In another, taken at a baseball game, it not only straightened the image, but made it horizontal instead of the dreaded iPhone vertical. I found both results pleasing.

All in all, I found Photos to be such an improvement over iPhoto that I wonder why Apple didn’t create it years ago.

iCloud Photo Library

You don’t have to use the new iCloud photo-syncing service with Photos — but if you do, there are advantages.

All your full-sized original photos are stored in the cloud, and the local copies on your mobile devices are scaled-down versions that take up less space but are optimized to look good on the device’s screen.

Not only that, but edits made on one Apple device almost instantly show up on all the others. For instance, on my iPhone, I cropped a photo of a watch band and applied a black-and-white filter to it, and the altered image promptly showed up on my Mac.

It does cost money. Apple gives you five gigabytes of iCloud storage free, but charges from 99 cents a month for 20GB, up to $20 a month for one terabyte. Storage space for your photos is shared with storage space for other iCloud services like Mail, backups and documents.

But the cloud library’s advantages only matter if it works. And, for me, it didn’t, until Apple fixed it, after I brought my problem to the company’s attention while reporting this review.

At first, my MacBook Air uploaded pictures to the cloud slowly but steadily. But then, after a couple days, the process simply froze. Many, many photos went missing from my mobile devices, and photo edits wouldn’t sync.

Apple asked me to send them logs from my Mac for diagnostic purposes, and I did. It turns out I had run into a rare bug in which one of my photos from 2010 had somehow been duplicated on their servers hundreds of times, once uploaded.

Apple guessed that it may have been due to a bug in an old version of iPhoto which corrupted my library — even though I couldn’t see the duplicates on my end. They explained that when the new syncing service encountered the many duplicates, it stopped syncing. After investigating, Apple performed a workaround to resume the syncing.

I’m not sure exactly what to blame, but I doubt an average consumer who wasn’t writing a review would have been able to quickly resolve such a problem. And even when syncing was working, it was fairly slow, so my devices still aren’t all in sync.

But one of my Re/code colleagues has also switched on iCloud Photo Library, and her transition was smooth. So your experience may vary.

Bottom line: I can easily recommend Photos, but you’re taking a chance with iCloud Photo Library.