I've replaced my iPhone. The Nexus S with Gingerbread didn't convince me but Ice Cream Sandwich won me over. There are some things that are better (big screen, notification light, multitasking, keyboard) and some things that are worse (lock/volume buttons, browser, most third-party apps), but what really won me over was the Google apps: Maps + Navigation, GMail, Talk, Reader, and Voice. Since switching I've also discovered Google+ instant upload for photos is more convenient than I expected, and Google Music works really well. Also, since this phone came from Google, it's unlocked and I can tether for free :-)