Well, as some of you may now, saw the avant premiere yesterday, and it's not much far from what shadow said.
++ "Derezzed" in my pants when Daft Punk made their cameo,
the DJ's in the virtual city's "discoteque". The fighting scene in there was just great with "Derezzed" on the background music. 
The original score as a whole is just flawless.
++ Olivia Wilde. Fuck yea.
++ Loved the Michael Sheen's parts. This guy (in just 15 minutes) stole the movie for me.
++ Also the "Pole Position", "Pac-Man" MIDIs
-- The 3d is only in the Grid parts; the rest is plain 2D
-- The movie gets kinda slow at the middle, sags for around 20 mins
But it's a solid 3.5/5 for me.