I have had my 920 for a little over a week and had my first freeze. I was in Words with Friends and I'm pretty sure this is due to the app as it performs pretty shoddy anyway and I have seen a few other posts saying freezes may be due to WWF. I have no issues with anything else on the phone except for battery and tweaks fixed that issue. I expect MS and Nokia updates will also resolve battery issues for new phones.
A few thoughts, MS should better isolate app space and memory as a bad app should not be able to freeze your OS, and MS should take Zynga to task on this. I am not impressed at all with WWF on WP8. MS paid many developers to port popular mobile apps to WP8 and Zynga appears to have said sure, give us the money, and then quickly threw out a crappy port. The turn updates are slow, some in-game messages look like a generic message class, notices (like invalid word) appear at the top of the screen versus a nice alert window and then disappear before you notice them, pressing tiles sometimes doesn't respond, and every now and then a generic message window pops up in the middle of a game and disappears before you even have time to read it. Zynga, fix WWF, you can tell this a rushed product.
A few thoughts, MS should better isolate app space and memory as a bad app should not be able to freeze your OS, and MS should take Zynga to task on this. I am not impressed at all with WWF on WP8. MS paid many developers to port popular mobile apps to WP8 and Zynga appears to have said sure, give us the money, and then quickly threw out a crappy port. The turn updates are slow, some in-game messages look like a generic message class, notices (like invalid word) appear at the top of the screen versus a nice alert window and then disappear before you notice them, pressing tiles sometimes doesn't respond, and every now and then a generic message window pops up in the middle of a game and disappears before you even have time to read it. Zynga, fix WWF, you can tell this a rushed product.