There's no comparison, really. ME2 is not even a RPG.
/can of worms
Story driven, cover based combat, cinematic approach, character levelling with activated combat skills, game changing choices. I don't want to get into whether it is an RPG or not, as I did not make that point. I compare the two based on the above and, with the exception of the fact that ME2 was squad based and lacked true stealth, I feel that the comparison is a fairly direct one.
ME2 was universally loved by critics it seems, unlike AP. I enjoyed AP so much, however, that I registered on this site at 4am-ish (end of first play through) to post.
To answer an earlier poster, I don't use the word masterpiece lightly. I have never written it on an internet forum before, in fact! This is totally subjective, of course: That is just how much I enjoyed the game.