About 80h in the game, i have finished all of the side quests, and have all the team members loyal, at level 25. There are still a couple of weapons and abilities, which could be upgraded for one level, but i have no more money for them, and no missions left where i could get money, so i guess it's so by the design. Very nice.
I like how the game locations are organized around the ship, and i find upgrading weapons much preferable to changing them - saves time, and improves the game flow.
It is also interesting to read various planet descriptions, though in some rare cases, they might have not been thought too well, but nevertheless i find most if not all of them possible and in the realm of the known facts. There is some room for speculation, which is being explored of course, and i'm taking FTL, element zero and various powers out of this fact-picture. I would very much like to see someone with more knowledge in astro-physics and astro-chemistry to check the game, to either confirm or invalidate my assumptions.
Game introduces a lot of science facts and words, and i think it is possible that some of the players might actually check them on Wiki, to see what is and what is not, which is recommended in any case.
There are also fuel depots, where you can buy - guess what - fuel and probes for planetary prospecting.
There are, of course, a lot of simplifications.
I'm playing this game as a good guy, Paragon, but had to press Renegade (dark side) button at least once, to stay honest to myself. Neutral options make sense in all cases, though they can be a bit cold.
Morality is a rather big issue in this game, and i'm still chewing on my impressions about it. Good decisions are in general harder to accomplish - if that might be a lesson - and their goodness might be questioned by the perspective - i think pirates might object calling a destruction of their bases, killing everyone there, including bots, dogs and vermin, hacking into every hackable thing and plundering anything that could be moved or plundered, a good thing. Beware you naughty galactic scum - all your bases are belong to i and your time draws nigh !
I had no problems in any of the quests, and had seen no bugs worth mentioning that i couldn't shoot at and get rid of. I had one crash due to the overheating of my graphic card, but no other issues. Game can get extremely slow if there isn't enough memory, as i found out after running in parallel a program which took most of the free RAM - you don't want that.
My box is dual core AMD at 2.6 GHz, 2G RAM, GForce 7600 GS, WinXP SP2 patched SP3.
There are no memory leaks, as game runs ok even after a couple of days without restart - all in all, good job Bioware, so far 9/10.
Game uses Unreal 3 game engine, so i expect a lot of moding tools, when i will look for them.
I have still to check downloadable content, perhaps something about it later.
Very good reference and source of game information :
http://masseffect.wikia.com/wiki/Mass_Effect_2