I don't have 3 yet but I just played 2 on the ps3 without ever playing 1 and of course I have no clue why Shepherd was on that ship, etc but the game was still fun. I know with 3, the decisions made in 2 will have an impact on 3 so without playing 2 and having a save game I guess it will just be a generic 3..??
I may get 3 this weekend. Debating if i want to wait for someone to run it on sale for $40 or just pay the $60