In Mass Effect 2 they decided to amplify all of the weaknesses of the first game while toning down the good things, and added in some sort of "minigame" where all you do is move your mouse around a colored sphere, very slowly.
Well, everybody has different preferences, but I definitely didn't feel that way. They made the combat quite a bit more interesting, and the personal stories were good. But I felt they really fell flat on the main story. Most of the time you wouldn't even know there was this big galactic threat going on, and I really disliked the ending. Overall, I still enjoy the game. It just isn't near the best.
Mass Effect 3, however, I'm really getting into. With the combat, it feels like it's a cross between ME1 and ME2, taking the best from both. Autohealing is minimal, and acts much more like ME1. Enemies are tough and fast, like in ME2. There's more choice than ever about which weapons you take along, and there are quite a bit of customization options for the weapons.
I'm also really liking the integration of the main story with everything. It really feels like you're in a galaxy at war, and, at least in my first playthrough, it really feels tied together.
I'm almost at the end now, so we'll see how that wraps up. But overall I am very happy with this game, and will probably play it many more times.
Edit: Just finished the game. Really liked the ending, personally. Very satisfying.