I remember the exact date I bought it, because it was the last time Apple updated the iPhone. Unlike Android devices, there is only one new iPhone and one new iPad a year. That doesn’t offer a lot of choice but it does make things simpler.

There are things I really like about Android, including how easy it is to configure a new phone. Type in your Google  credentials and, within minutes, the phone downloads all your email, contact information and even some personalization features via the cloud. Some models I’ve tested even automatically imported the “wall paper” photo that I had on my previous phone.

Google offers Android to multiple vendors, so there are plenty of phone choices that all — in theory — can run the same operating system and the same apps. Partly because of the competition, there are plenty of Android phones that are less expensive than iPhones, not only for end-users but also for the carriers that typically subsidize the end-user price in exchange for signing a two-year contract. Android is doing quite well; the latest figures from ComScore give it 51 percent of the U.S. smartphone market, while Apple has 31 percent and Blackberry 12 percent.

Like Apple, Google has amassed an enormous developer base, and there are now more than 443,000 Android apps, according to AppBrain.

There are also a lot of different devices. OpenSignalMaps, a service that helps users find the best cell phone signals in their area, has been logging devices that download its app and has found “599 distinct brands” of Android devices and nearly 4,000 distinct models.

Apple, on the other hand, so far has just one screen siz​e for its iPhone and a single tablet screen siz​e, regardless of which generation device you have. And, even though Apple refreshes its iPhone and iPad annually, the number of Apple tablet and phone models out there can still be counted with two hands.

Having so many Android players with so many distinct devices definitely has its advantages. Amazon, for example, was able to create its very popular $199 Kindle Fire tablet, which runs a heavily customized version of Android that not only has a distinct user interface but doesn’t necessarily run off-the-shelf Android software. Amazon created its own eco-system around the Kindle Fire with its own app store and its own rules for developers.

The open Android system also allowed Samsung to create a diversity of its own devices with a range of screen siz​es. I like the new Samsung Galaxy Tab 2 because, like the Kindle Fire, it’s a full featured tablet yet small enough to fit in a coat pocket. And because it’s smaller and lighter, I find myself using my Kindle Fire more often than my iPad. I hope the rumors that Apple is developing a 7-inch iPad turn out to be true.

siz​e also matters with phones, and sometimes bigger is indeed better. If you’re using your phone to watch video or read eBooks then having a 5.3 inch Galaxy Note might be perfect.

But despite all the positives, the diversity of the Android ecosystem has it downsides. The world of Android is extremely fragmented, not only with a wide variety of hardware devices but with multiple versions of the Android operating system and — my pet peeve — customized interfaces that make it harder to switch between devices.

The fragmentation of hardware makes it harder to get everyone using the latest operating system. Unlike PCs, users can’t just upgrade an operating system at will. Users have to wait for their carrier to release an upgrade, and that can take forever. Even new phones are coming out with older Android versions with no clear update path. It’s also harder to app developers, not only because of the diversity of operating system versions but also hardware differences, including so many screen siz​es.

And to make matters worse, handset makers love to customize the user interface with “skins” like Samsung’s “TouchWhiz,” LG’s Optimus and HTC Sense. Each of these skins has its pluses and minuses but I’d be happier with a single user interface from Google, which in my opinion does a better job than the hardware makers when it comes to interface design.

But despite my complaints, I remain optimistic about Android. Problems aside, diversity and openness breed innovation and, over time, I expect there to emerge a more harmonious Android ecosystem. But I got tired of waiting, which is why I bought that iPhone 4S.