Everything else I've read about deadspace 3 = "they fucked it up"
did you play 1 or 2?
Yes, I played both 1 and 2. They definately made a lot of changes, which is probably what pissed off their core audience. It feels very different than the first two. At first I didn't like that it felt different, but once I adapted to the changes, I liked it better than the first two. They also included a "classic mode" so you can play it more in the spirit of the first two, if you like.
What I liked about it was that the story was great, after my feeling that the story in two didn't really do much...we'll throw Isaac on some space station, throw in a new necromorph infection, and boom, story done. Without spoiling anything, 3 widens the scope of the necromorph plague and answers all the questions that needed answered in a third game. 3 is also more visually interesting, with environments other than "inside of a crippled spaceship/spacestation" to explore and fight in. I also dug the archeology aspect of the plot, being a history major and all.
I'm not sure what's not to like, other than the changes to the weapon system. It was annoying not to be able to do the co-op sidequests since no one I know has the game, but that's no big deal to me. What did people complain about?