I managed to get some hands on with FIFA 13 and, as a relatively casual player, I found the changes to be slight, but significant. The most noticeable change is definitely first touches. Not all players can bring long passes under instant control ala Dennis Bergkamp, so there's a certain skill now in being aware of who you're passing to. But you won't have to take my word for it — there's a new demo on the way, and it should arrive later today!
The demo is already available in the UK, with North American players to follow. I'm doing some double checking with EA locally to find out precisely when we'll get access, but I'm sure that'll be a formality. Either we get the demo today, or tomorrow at some point. I'll update as soon as I hear the official word.