I think ME2's great reviews were mostly driven by the excellent cast of memorable characters you got to assemble throughout the game. Such an upgrade over the BioWare trademark mild soup of forgettables in ME1, and also the biggest reason ME3 was maligned after relegating most of those beloved characters to a 5-minute scene.
That’s right. I’ve seen arguments over which scheme is better, but the second game’s scheme is definitely more orthodox.
I also keep hearing ME1’s combat described as “clunky” and ME2’s as “smoother”. Without much experience with this type of game, I think I just don’t have the skills to feel the difference.