So I managed to get my 4s late last week from Fido. So far I am quite impressed. Migrating from a 3G makes the speed seem simply incredible. The ability to multitask, something that most of you probably take for granted, is also quite nice. I can now listen to Tunein Radio and check my email without exiting the app and stopping playback. It's the little things...
Siri seems like it has a lot of potential, particularly while driving and making a call or sending a quick text. She'll actually read out new, received text messages for you as well. Otherwise, I honestly don't find it that useful (beyond the novelty factor) while not driving, as I can read the time, weather, email, texts, etc. faster by doing it manually. It will be nice when some of the location-based features work in Canada though.