Interesting to see that there are a few iPhone-to-Android-and-back-again switchers here, myself included.
Had the iPhone 3G and 3Gs, switched to a Nexus One and swore I'd never return to iPhone and turned into somewhat of an Android fanboy.
I loved the high customisability, the widgets, notification system, and the overall euphoric hippy feeling associated with it being an open platform.
And then Froyo came out.
I was massively excited about the imminent prospect of updating to Froyo. But despite reports of it being delivered over the air to other Nexus One devices, mine didn't seem to be receiving the update. Then I dug a little deeper, done a bit of research, and it turned out I wasn't receiving the update because Vodafone were busy preparing their own version of Froyo, tinkering it to be "optimised" for their network, with no ETA and an indefinite waiting time. That's when I stopped seeing Android through rose tinted glasses.
HTC Desire users on Vodafone had it much worse. They received an OTA update which done nothing but riddled the device with Vodafone's proprietary crapware.
Eventually, a couple of months later, the Froyo update came but I had already ended up arguing my way out of the contract and returning the phone.
All of a sudden the prospect of a walled garden, especially one where carriers and their interference and bloatware weren't allowed, didn't seem like such a bad thing after all.
The updates in iOS 4.0 were, in my eyes, enough to narrow the lead Android had over iOS, and in my opinion there is simply no Android smartphone out there which comes close to the design and build quality of iPhone 4.
Now that I have an iPhone 4 I couldn't be happier. I forgot about lots of iOS' little nicities which I missed while being on Android, such as the way better implementation of copy and paste, the overall buttery smoothness of the UI and most importantly for me, the far better Mail application.
Having said all that, I think it's great that we've finally got decent alternatives to iPhones such as Android and WP7 to give Apple a bit of a kick up the butt and increase competition, (for a while I really didn't like Apple's attitude and the hints of a monopolistic monster they appeared to be turning into) and I'm really looking forward to seeing Gingerbread and future iterations of Android to see if they can tempt me back.