Mass Effect 2

I bought it yesterday. Haven't installed it yet, I'm still debating if I should play through the first one again to use the character in the new one.... Does it make a difference? All the reviews and previews say you don't get the full effect unless you use your character from the first.
 
Just played an hour, and loving it so far! Good thing I kept the endgame save from Mass Effect, as that gave me 120k credits to start with :D