For the record, I beat it that fast because I took the bad route on everything, and killed everyone every chance I got, so it sped the game up VERY quickly. There was no extended versions of any of the main points and there wasnt any sidequests i did unless it would specifically kill then.
I was at the max level for renegade or whatever where you can get to do the red options before i completed the second citidel (right before the end when they trap you), so there wasn't much I could do other than go straight for saren.
I'm not really saying it's short, I'm just saying he asked how long it took for me to beat it and i told him how long.
Granted, I am playing it over doing everything sidequest and pretty paragon about everything and im flehsed out to 6 hours already before i even get off the first planet I go to.