Let another Android phone user jump in here.
I had an iPhone 4, then switched to a Samsung Galaxy II using Android 2.3. I thought it was going to afford me much more configurability, and it does, but it's a little too open, and definitely unstable. Your looking at an OS that has to support multiple pieces of phone technology, and now with ICS, tablets too. Some of the problems I've encountered:
1 - at maximum setting, screen is very dim when outside during the day.
2 - occasionally the phone will just power off for no reason, sometimes powering right back on, sometimes it must be manually powered on.
3 - a couple times I've plugged the phone in to the charger, it indicates its charging, only to pick it up an hour later and it's lost power instead of gained charge.
4 - when leaving the house and disabling wifi, sometimes apps such as mail and browser no longer have a network connection. Turning wifi on and off or switching to airplane mode on and off sometimes works. Other times its necessary to power phone off and on to get it working.
5 - battery life is very poor and I've even ensured to occasionally allow battery to lose all power before recharging.
6 - find the gps in the device to be somewhat slow to respond.
Stick with your iPhone....I'm definitely going back to a phone and an OS which were meant for each other, and DEPENDABILITY and STABILITY!
Feel free to PM me.