I got it a couple of weeks ago and paid £29.99 so I was bit gutted when I saw this thread.
It is an enjoyable romp and I would heartily recommend it from the single player side of things, I havent played it online so couldnt comment on that side of things!
The single player game is OK, Graphics are quite good with some nice effects. The Xbox Live experience with multiplayer is what sets this game apart. I prefer it to GOW for a bit of a larf online.
Try the downloadable demos (online and single player) to get a feel for the differences. probably worth mentioning that the demos were released waaay before the game hit the streets (I believe), and the graphics have been tweaked a bit and and are much prettier in the game release. (or perhaps it's just my eyes..)
bottom line if you have xbox live, it's well worth 20 quid.. if not, it's a decent enough 3rd person shooter, better than a lot of games on the platform, but a little repetitive in single player mode..