Honestly, I feel that everybody makes the mistake of viewing this game as a horror game, including the designers/developers, instead of a human drama with a survival horror background. The best part of the game was the beginning when there were other people experiencing the shit going down. Watching the huge crowd of people runing and being massacred by a horde of nercromorphs early on actually hit a bit of a note for me. I thought that instead of sticking Issac in a variety of dull rooms with a variety of people with claws for tits, they would focus on the panic and hysteria of the outbreak, with the crawling through dull rooms still there, but intermixed with dealing with a panicked crowd of survivors. I realize that it would be hard to do, but they could have at least given it a bit of a try. For example, there could have been a bit early on where Issac has to race through a crowd of people moving in the opposite direction in order to seal off a large doorway which necromorphs are swarming through in order to try to turn the crowd into a collection of decapitated bits. That scene would both be interesting from a gameplay perspective, a storytelling perspective, and it would also be pretty moving, especially if you added something like Issac being stuck on the other side of the blast door. This isn't the most well developed idea, but I feel that if Visceral tried to incoporate it on some shape or form, it probably would have worked.
I also feel that how they choose to represent Issac's dementia early in the game was somewhat of a mistake. For example, there is one part where you are going under a walkway to reach the tram, and about halfway under the screen goes all red and blurry. When you get to the tram you see Nicole, his girlfriend, in her evil bloody corpse version, and then she vanishes. I feel a more effective way of doing that would be to merely have Nicole be there, for us to unexpectedly stumble upon, and the red blurriness to only appear when she disappears. It would have made it less expected, and made it harder to determine when Issac is suffering from a delusion or not.
That being said, I still think that Dead Space 2 was a well designed game, and although they made a few mistakes, I feel that it is a definite improvement over the first. The characters are better developed and the gameplay is more balanced (the plasma rifle is no longer useless, and the plasma cutter is no longer strictly better than everything else). When judged by its own merits, the game is very good, not great, but definitely worth the money. It also stands up on its single player alone, which is more than the mass-produced machine of call of duty can say. Yet at the same time I'm disapointed, which seems to be a recurring theme recently (before dead space, the last new game I purchased was Golden Sun: Dark Dawn, which while good on its own, was very weak compared to its predecessors. If Golden Suns 1 and 2 were like Final Fantasy 6 & 7, Dark Dawn was at about the level of 5 and 8). I feel that if Visceral had made different design choices, Dead Space 2 could easily have become one of the new pillars of the "games as art" argument, as it had so much potential.
However, ultimately, I look forward to seeing Dead Space 3, because it seems that if Visceral continues to improve, they will eventually be able to realize the potential of the series. Its the same reason I keep on buying the Fable games, because I'm convinced that Peter will eventually get things right, and that by about Fable 7 or Dead Space 9, they will be able to produce something so perfect that lesser designers begin trying to rip it off so rapidly that they develop faster than light travel.