I don't think I can properly judge this game after just one playthrough. Two or maybe even three will be necessary. What I can say right now is that there's no substantial improvements 2 makes to 1. I'm not a fan of the simplified RPG elements, or the change from heat gauges to ammo, and I think 1 was a lot more tightly written.
That being said, though, it's still Mass Effect 2. Just because I didn't like some of the changes doesn't mean it doesn't kick ass anyways. A masterclass in atmosphere and consequence, best described as "Bold in a way that games before and since haven't achieved."