Played it an loved it. Very worth the time.
The game itself is about Comander Shephard, a soldier for the earth alliance. The game is about how you track down a Turian (sp?) Specter (high military official with the citadel alliance) who is bent on conquering the known galaxy. Sounds cliche but its not really.
Heres a review of it to help explain some things I left out and such.
http://www.gametrailers.com/player/28091.html