I don't usually have much time for video games anymore, but playing this game was more like reading an amazing book than playing the average mindless shooter. This is true art.
Storyline is very deep; It will draw you in to the point where you are excited to progress and see what the characters will do next; You will find yourself completely engrossed in their personalities, histories, and the adventures they go through together.
The only real con I can think of is that one of the key traits of the first Mass Effect was just massive maps; They have been shrunk down and just don't feel as expansive anymore.