So I've been on a console game kick lately and have a slew of reviews to write up, but since I just finished ME2, I wanted to get my thoughts out before they start to fade. I'll try not to include any specific plot points so I don't spoil anyone's fun. Having played the first Mass Effect, I was already a bit invested in the series and when I finally started the sequel, the opening sequence got me hooked. It felt like I had just started a movie and was already at the edge of my seat when the opening credits started.
One big annoyance I had with the first one was that there was far too much planetary exploration. You'd come across an unexplored planet and have to set down in your dune buggy vehicle and roll all over the place to gather up resources and occasionally kill some baddies. They've streamlined that in the sequel. There's no more dune buggy exploration (unless you download the Firewalker DLC. protip: not worth it) and you can do your resource mining from space. The "hacking" and "bypassing" mini-games are a little better this time around.
I played as soldier class, but my friend who played through as adept told me that the adept biotic skills have undergone significant improvement. You can now "bend" your abilities and can even use them around corners. If I ever make it to a second play through, I'm going full renegade adept.
The game did seem a bit short as you'll find that most of your side quests are just "loyalty" missions to get individual crew members to become loyal to you. I wish there was a bit more variety, but I guess that's what DLC is for nowadays... Another complaint is that the game is still ultra linear and your paragon/renegade choices don't seem to do much to vary the plot. I hope Mass Effect 3 has a bit more variety and maybe multiple endings depending on your in-game choices.
In conclusion, I'd have to say that I liked the game (despite my gripes) and it kept me entertained for the week I played it. I'm a fan of the storyline so I can't wait to see what happens in the next game. There's even rumors of an online version of Mass Effect which would be kinda cool. Bioware has succeeded yet again in making a fantastic product, but perhaps they're leaving some of the biggest surprises for the 3rd game (more weapons, better quest variety, multiple endings, etc). I give this game an A.