I'm in the UK and bought it from www.gamekeys4u.net - it sounds like a dodgy website but it has a very good score on TrustPilot and my brother and I both bought the game there and activated it on Steam without issue. It's annoying that Ubisoft has decided to mess things up with the Steam UK release but they did exactly the same thing with Far Cry 2 (it turned up around a week after launch).
As for the game, I'm really enjoying it so far. The graphics are exceptional and the gameplay is basically just Skyrim as a first person (i.e. it's brilliant). There are a few SLI / driver issues but I'm sure they'll be fixed promptly (at least SLI works, unlike Borderlands 2 at launch).