I saw it on friday. (The second of the third, dun dun dun!) I thought it was really, good, especially considering Jim Carrey being in it, I've generally avoided his films, but I'm glad I saw this one. Throughout the film, it was consistently just about clever enough for me to be figuring things out, but not all of it.
I wouldn't say it's my favourite movie that I've seen this year (because Blood Diamond was absoloubtly incredible) but it is certainly something that I would recommend to anyone wanting a film that's easy to watch, but still interesting.
Also, you see the number 23 everywhere after you leave the cinema.