Not really sure how far I'm into it, but I'm loving it so far. I think mostly I just love the art direction. There are those that are going to blast it for being "Bioshock", however..there are nods, but this isn't Bioshock. The story is pretty cool so far, but the environment is what shines.
From what I've played so far, it is pretty straight forward and linear. Not necessarily a bad thing, but it is not Dishonored. The story seems to be key here.
Only real gripe is the save system. Absolutely hate it because half the time I can't tell when it saved last. It doesn't always pop a display up.
One other complaint is when you die..you don't really come back where you died..but..nearby and things aren't the same as when you died, a few times that was confusing.
Riding the rail system..is...on rails, but not really on rails. You can move around, speedup/slowdown, turn around, etc. Pretty fun, but limited so far.