Bought the game for Xbox a couple days ago, and have been playing it on and off since then. A few points that stand out in my opinion:
COMBAT: fast-paced, kill-or-be-killed. I haven't played Bioshock or Rage, so the best comparison I have would be
Skyrim meets Fable III. Most folks reading this will probably find that assessment very odd, but the twitchy, super human-esque swordplay strikes me so.
DIALOGUE AND STORY: Meh. The setting is excellent, and probably underrated for a true action-based platformer. The story itself is nothing particularly compelling; tried and true, but not quite polished or well enough delivered to be called "classic." And although it would be terribly cliche, I in the camp that believes the game's atmosphere could have benefited greatly from traditional English rather than flat American accents.
STEALTH: "Meh," is my honest opinion. In terms of abilities, mission layout, and objectives Dishonored is rich with possibilities. What really crashes it in my opinion, is 1.) a moderately weak to utterly shameful/hilarious AI and 2.) poor implementation.
On the first count, you have all the classic examples of stealth game-breakers, including a few that, say, Metal Gear Solid and even Skyrim have worked around. To begin with, most guards and other enemies seem to have a maximum peripheral detection range of about 10 feet, or otherwise don't seem to care when you slit their comrade's throat while they smoke a cigarette. In another instance, you might find yourself with the advantage of height over your unwitting adversaries, and decide to pick one off. After doing so, the remaining enemy may happen to notice and path to engage you... right into the wall below. This of course means that you will be unable to drop down and kill him stealthily, or would, if he were not soon to be overcome with "amnesia" (which, due to the flavoring of the voice acting, plays out more like sudden Apathy Syndrome) and sulk away with his back turned.
As for implementation, my criticism is that many of the covert abilities and pathways just aren't necessary, at least not on normal difficulty. You could take the long road around that checkpoint, but why bother? Shoot that guard in the head, and cut the others down in a few quick motions and be done with it. It is, of course, wonderful that we have both options, but leaves a bad aftertaste in my mouth and a sense that the gameplay is quite shallow. Maybe that will change as I progress.
Anyway, my two cents.