Death is only the beginning.
Your save file will update the sequel according to the choices you made in the previous game, and the continuity and immersion achieved by this is simply incredible. All the characters you became attached to while playing ME continue to exist, even those who died thanks to your decisions. Some of them will join your team once again, others will come back as memories and guilt. On top of that, new characters are introduced. Most of these are great, a couple - a Salarian commando-scientist and a Drell assassin - are brilliant. On the whole, the cast has been greatly upgraded for the sequel, including the voice acting. Martin Sheen, Carry Ann Moss and Michael Hogan are just a few of the big name actors lending their talents.
Though very well acted and shot, Mass Effect 2, like the first game is a bit light on the story. The lore and background is still better than average, but the story that you personally take part in is, again, pretty thin. You will probably spend around 30 hours on your first play through, but all that really happens is you travel around Milky Way to assemble your team and once that's done, you move on to the endgame. Now, the endgame is one of the best such sequences in any game, but it just feels like there is a lot more story potential there, even within the context and boundaries set by the in game universe. For instance, Specters and the Citadel Council are barely mentioned in the game, and the choice you made at the end of Mass Effect, which seemed like such a big deal at the time, turned out to be, as the Vorcha say, "meh," at least in terms of pure gameplay. Shepard can be "reinstated" as Specter if he wants, but that basically means squat. Politics could have played a larger role. Other subplots could have been introduced as well. You encounter several different merc organizations during your quest and side missions, but all of them are just meat, with no other purpose than to be an obstacle between you and your objective. With such a vast galaxy out there, it's a shame there isn't more to do.
Still, I have to say that on the whole, and even with the loss of MAKO, the exploration aspect has been greatly improved. Where it was pretty much completely pointless and tiresome in the first game, the new research system requires the minerals you find to implement upgrades. And you really want to be upgraded for the endgame. A lot of people complained about the mining minigame, but I personally have no beef with it. It may not be the funnest activity out there, but hey, if you want upgrades, if you want to succeed and keep your people alive, do a little work. The other two minigames are for hacking terminals and bypassing security. Both are fun, but a bit easy. A slightly quicker timer would have helped to bring about some intensity, in my opinion.
Which brings me to my main complaint, aside from the story. The clunky combat of the first game has been polished and streamlined so much that it became too easy. There are higher difficulty levels available, but the game should feel just right on normal difficulty setting, and ME2 does not. Especially since you gain immediate access to Heavy Weapons, a new feature that feels a bit too much like a noob free pass. No one will twist your arm to use it, but just having it there kills the intensity.
Coming back to characters, old and new, and how awesome they are, I have to mention the romance. Following puzzlingly popular demands, aside from new human objects of desire, you now have the option of romancing certain alien species that were deemed too weird by the first game. The trade off, apparently, was that the romantic scenes had to be made even more tame. "Partial Nudity" is no longer on the menu, and I was surprised the chained and beaten monkeys in the ERSB basement did not come up with something like "Partial Underwear" to replace it. The sad saga of sex in "mature" games continues as Earth spins its way into the second decade of the 21st century.
Briefly now on other changes:
-Inventory and loot removed completely.
-Money system improved, more meaningful
-Cinematic effect improved
-Level design improved; recycled identical floor plans replaced with levels that are more fun, but full of inexplicable cover.
-Graphics improved
-Normandy improved
-Side quests improved
In closing I'll say that although not perfect, on the whole ME2 is a better game than ME and the best SciFi-themed Bioware product to date. Does the removal of inventory and loot make it less of an RPG and more of an FPS? I don't believe so. Choices and their effect on the gameplay, character interaction, story, atmosphere - these are more important to an RPG in my book than searching through chests. Is ME2 a better game than Dragon Age? No.