I'm going to be a doubleconvert. I was an iphone 3g, 3gs, 4 user. I got sick of the 3.5" screen and went to the GSII about 2 weeks ago. I LOVE the screen, guh I so love the screen. I love Swype as well! These two things are huge plus's to me.
However .. I am likely going back to the iphone 4s, why? Simple, it works 100% of the time. In the 3 years I had iPhones I think I had a total of 2 crashes and 2 lockups.
In the two weeks i've had the GS2 i've had to reboot 6 times, and force close a dozen applications. I haven't rooted, haven't done anything super fancy to the phone. MMS locks up all the time when taking pictures, I find apps that don't work with the phone. Annoying, and a lot of this comes down to iOS vs Android.
iOS simply works, you can't customize it for a , good luck if you want a new feature, but you can rely on it to be there when you need it. Applications work for everything, huge advantage only having to support 5-6 different cpu/gpu combinations and like 2 resolutions on iphone and 1 on ipad compared to the hundreads of combinations of cpu/gpu/resolution Android has to contend with.
I almost wish Android had not gone open source, that Google had gone the Apple route, made their own hardware and just done it differently. Sigh .. there is no question the 'hardware' of the new android phones is going to outdistance the iPhone's, but until they can make the OS stable, the app store not so fragmented, there are going to be problems like this that can't be surmounted with more cpu cycles.