Bioware has succeeded in creating an amazing and groundbreaking game, and started a new franchise off on a very strong note.
Story
The story is epic. Like you must single-handedly save the universe from total annihilation epic. The real-time cutscenes are some of the best in any game. The conversation system feels much more streamlined than the typical dialogue tree found in most RPGs. You pick an abbreviated statement that sums up the tone of the response or question. The universe is really fleshed out and there is a lot to discover. The sidequests are quite a departure from the main storyline, and don't have nearly the same cinematic feel.
Gameplay
There are 6 classes to choose from utilizing 3 main skill areas: Combat, Tech and Biotics (not the Force!).
The combat is a realtime Third Person Shooter/RPG hybrid. You choose 2 squadmates to join you for all combat areas. Action can be paused to use your or your squadmates abilities, which can have a significant impact on the course of combat. Effective use of tech and biotic abilities is necessary to progress on the harder difficulties.
There are vehicle sections using the MAKO, an armored personnel carrier. These sections are probably the weakest, gameplay wise, in the game. The MAKO can be a pain to control at times.
Graphics
The game uses the Unreal Engine 3 and has some of the best character models of any game. The game uses an default, optional grain filter that gives it a more cinematic look. The game does suffer from texture pop at times, mostly immediately after loading, but occasionally at other times, even during cutscenes. The frame is usually pretty consistent, but will suffer during especially explodey combat. Overall it is one of the best looking games on the 360.
Conclusion
For me this was easily my game of the year for 2007. I loved the scifi universe and I think the combat system is amazing. I played through three times to complete the game on the most difficult level. While very challenging, I never felt the AI was being artificially cheap to seem harder. I think this is Bioware's best work to date, and I can't wait for more.