I really love the personal story Isaac goes through, and I think Isaac as a character is fantastic. My only problem is that, when going through the sprawl, there are a bunch of moments where there are people screaming for help, but you can never interact with them, they're simply there to help the atmosphere. Maybe there doesn't need to be an aspect of the game where you help some random individual, like a mini game or something, but I wish there was even more strong points to what emotions the game can bring; anger, sadness, what have you.
So far, they have it going strong, and some of the things Isaac says near the end always sends shivers down my spine since it works so effectively. People get it wrong, Isaac isn't simply just walking around like a dog as people tell him to do something. For most of the time, he's in control. See here at 2:22 to 2:35. If he didn't do this stuff, what would be the point of the games story? I can agree with number three, but I sure as heck hope you're not saying that venturing through The Sprawl was boring.
There are a few aspects that I still can't put my finger on that makes me a little bit disappointed with the sequel, but Dead Space 2 is so good that may just be the reason why I can't pin-point it. It may be because I had two totally different feelings of when I beat the first Dead Space and the second. Two both great feelings, but that's what I'm not sure about. I remember feeling a bit of sorrow at the end of Dead Space, 'cause everything/everyone you grow to like over the course of the game is done for. Like even though Kendra was bad, it was sad to see her die in such a way. Dead Space is just so immersive. I love 'em!