I recently switched from an iPhone to an Android and haven't looked back, even though I still see the iPhone as a best-in-class device. The best Android phones are just a few percentage points shy of the iPhone in usability, and the availability of Flash for Android alone makes up for that, IMHO. Even though I have a healthy dislike for Flash.
Add to that the fact that you can get an app written and deployed for Android in a fraction of the time it would take you on the iPhone...
- Because you're not required to use horrid tools like Objective C
- Because there are no imperious App Store overlords deciding the fate of your app's life or approval
- Because you don't need to make a several-thousands-of-dollars investment in Apple hardware and software
...and I think it's likely that Android will eclipse iPhone, not just in numbers of handsets (many orders of magnitude more coming for Android), but in mindshare, pop culture relevance, developer sentiment, and every other thing.
The iPhone will always be the phone that launched the smartphone revolution, and Apple and Steve Jobs have been well rewarded for it. Android to me represents the democritization of the iPhone, and the democritization of designer tech has always been the bane of Steve Jobs. Put another way: iOS devices are going to seem much less compelling when they've been copied, perfected, rebranded, and sold for half the price. It's Mac vs. PC all over again.