I regrettably installed ICS about a week ago, and I hate hate hate it. Not only do you have to jump through hoops to keep your battery from draining quickly, but you lose a lot of features, too. If anyone can help with any of these issues and lost features it would be greatly appreciated!
1) I can't figure out how to save a phone number to contacts from a text message. I've tried everything I could think of, and it doesn't seem to be an option.
2) The volume for texts and notifications does not get lower when you lower your ring volume. This is HUGE for me because I turn everything down low at bed time so it doesn't wake my kids up.
3) I downloaded the "Phone Info" app so that I could stay on 3G (after the "upgrade" the 4G seemed to be draining my battery much faster). I selected GSM/CDMA auto (prl) and immediately had issues. The biggest being that my Yahoo mail stopped automatically updating and notifying me. I also turned off notifications for Words with Friends and Hanging with Friends to save battery (didn't have a problem before ICS).
These are just a few of the issues, but I can probably learn to live with the rest. Thanks!