Everything and more... so far.
The gameplay is also traditional ME but the addition of weapon add ons (scopes, extended mags, damage modifiers) make the weapons more interesting and the guns are more realistic than in any previous entry in the series, they really feel like they pack a punch when you shoot them. The music so far (composed by the brilliant Clint Mansell) is excellent. Very moving and pumps you up to stop the reapers. Although I do miss jamming out to the "omega" theme song while in my private quarters.. for some reason the music selection for the shepherds private quarters sucks bad this time around.
Anyway, I'm going back to playing now... can't get enough. I don't know how the game will end but so far it's living up to the Mass Effect name and if you liked the other two game's you will love this one. I hope it ends well. I haven't touched MP yet and won't until I beat the SP.