Worth the purchase, then some...
The graphics of the game, something I think is important, though not critical, are probably some of the best on the system. You're probably looking at something in the MGS4/ MW2 area, or very possibly better. While I've never held off buying a game due to graphical issues, uncharted 2 definitely exceeds all expectations a person could have for a game of its nature.
The story, which is probably the reason a lot of you are interested in this game, is amazing. The ending takes a weird turn, but it stays consistant and (relatively) logical. The character development and interaction really shines through, and you'll find yourself laughing or jumping in your seat more than once.
The actual gameplay is, at heart, a platformer with third person shooter elements. Most of the levels revolve around jumping and climbing past obstacles, then shooting/ sneak attacking (something I thought was well done, considering) a number of bad guys that is usually fairly large. There are some moments where Uncharted 2 switches it up with level segments that focus on running from attack helicopters, tanks, and trucks, as well as levels that take place on a moving environment. One particularly awesome level has Drake jump from car to car on a the edge of a canyon while being shot at by enemy gunmen. At first, the introduction of flashback sequences cause the gameplay to take a slow start, but its all edge-of-your-seat from there.
Overall, I gave Uncharted 2 a 9.5. It is...really, very close to being perfect. However, there are some gameplay issues near the beginning, both with pacing and actual design, and a small amount of almost unimportant design related annoyances. Despite all of that, Uncharted 2 is easily worth more than you'll pay, and that isn't even taking into account the amazing multiplayer (which I didn't really go in to). Pick it up!