It's really not as bad as people are making out
Alot of people seem to complain that its just too hard to get into, and when you first start, that may be so. But when you've played it through once, and you start building up a good arsenal of weapons, and a great armory, then it really becomes a great, fun game.
Not to say that before then its not a good game. I mean, I played it all the way through in one sitting nearly, and immediately went on to my second play. The sense of achievement you get from getting a decent way through a level without dying is surprisingly great, and it drives you on, all the way through the game.
Alot of reviews also seem to suggest you have to have LIVE to get any real enjoyment from this game. That is so not true. If anything, (and this is just a presumption), I think it might even spoil it. You may lose out on good items, or the fighting may become too easy. I'd rather just keep playing it on my own, playing through numerous times. And that sense of achievements still going strong.
It may look like 9.0 is too high a rating, surrounded by all these lower scores, but I genuinely feel its worth it, as it has become one of my favorite 360 games of my collection.