The game tends to give you the Michael Bay one-liner treatment from time to time, and some of the plot twists are holding signal flares and waving their hands at you, but Dead Space 2 is a great improvement.
Also, the Dev team probably watched the ZP review of it, saying as you're no longer spending as much time in a ruined 'Nostromo' knockoff and instead in a place that looks livable and, if not for the evil beasties everywhere and the church/government/corporate power struggle, pretty cool to be. And even though some of the one-liners were pure cheese, it gives you the sense that under the armor is a guy who is scared out of his mind and trying to make up for it with bravado as the world crumbles around him.
I did enjoy the fact that they at least made Issac what they said he was. One of the things that bothered me was that the guy was supposed to be a skilled engineer, especially from the end-of-game logs that you get to read. He's said to be a top honors grad who put himself through school because his mom dropped their money and assets into the Church, yet all you see is a guy who can jump in space, operate doors and mod mining gear with obviously placed mod slots.
In the second game they finally show this. His first weapon, and one of the best weapons IMO, is a trusty plasma cutter that you jury-rig into existence. Doors have to be hacked by re-wiring the hardboards themselves, which even if possible today would take more than an intro course. It's good to see it put to work, as well as the other aspects of the character filled in, namely his relation with the Church and his PTSD from the events of the first game.
The enemies are craftier than before, though it's sad to see that most of them still use the 'Run at full speed with limbs flailing' tactic. On the harder modes, though, this gets tossed out the window as they will re-enter vents and come from behind to attack you. I found this out the hard way in several chapters on Survivalist, and knowing about it didn't help much on Zealot. Though you can skate by on Normal using the tried and true method of shooting straight ahead, that line of thought will get you torn apart on anything higher than that.
To sum up, it's one of the few games i'll take the time to play the New Game + on. The experience keeps you coming back to relive the scenes, and even going through the game with full modded weapons and the best suits won't help much on Zealot or Hard Core mode. Also, for everyone complaining that games are too easy, try Hard Core: You have 3 saves, no checkpoints and enemies can slaughter you faster than you can realize they've outflanked you and snuck up from behind. Good luck.