If you bought it for online play, read my comments.
The lobby system works fine but once you select a game to play in, things get a bit dodgy. Load times are *very* slow -- there is long delay before you even get into the actual game screen, which often means you lost your spot in the game and need to start the process over again. There is another long delay anytime a map loads. When the map is changed, you get another 30 second delay.
So my typical experience is this: get into the lobby, and spend 15-20 minutes seeking games, loading maps, waiting, retrying, etc. It's annoying, especially when the same process in Halo2, for example, takes maybe 30 seconds from power up.
When I do get into a game session, the game play is quite fun, but is a bit more run-n-gun than I enjoy in GR2:SS.
Oh, and there is one odd bug -- you cannot turn off voice through TV, it simply doesn't work, so you need to plug in your headset adapter just to silence the chatter.
I recommend renting before purchasing...I wish I would have saved that $50 for something else.