I think if it comes out in the same quality as the first we will have another gem (Since the saving issue that brought so much frustration in the previous title has already been mentioned to have been "Gone over and redone" by the developers).
Mass effect had a thrilling experience wrapped in great immersion (elevator scenes aside), a story line you felt like you affected and indeed did. It did alot of things right which alot of games fall off the deep end at and kept running with it, And I would expect more of the same.
Some changes I would throw in is actual space exporation. As great as the navigation system was, it was indeed boring. The whole fast travel option is nice but when its not an option it feels like I'm missing what could be a rich experience in space exploration.
So do i think Mass Effect 2 will impress? Yes I do, even if they do more of the same with a different story line, I believe I will still enjoy it