I have an iPad 1 that was adequate to surf the web on iOS 4.3, and I will never be able to downgrade to that version again. Now I have a brick on iOS 5 (unbearable out-of-memory crashes). I earn my money on iOS and I still can't really cheer at handcuffs. =/
The progress (some) OS vendors have made at keeping people current is really pretty fantastic when you compare to the situation 10 years ago.