If I would want to describe the recipe of this game, it would be something like this:
One part Thief, two parts Bioshock, one part Deus Ex - Human Revolution, and just a bit of Half Life 2 sprinkled on top.
In detail: The Game was good and really fun to play. The great number of possible solutions to each situation, the stealth aspect, the gadgets, the magic powers; they were all fun an really engaging to mess around with. However, there are some really blatant problems in the game's design.
First off, the stealth aspect is too enforced. If you want to have the "good ending", you are pretty much forced to sneak around and use nonlethal means, but that makes a lot of your gadgets and powers completely useless, including the great sword-fighting mechanics, and this arguably detract from the fun-factor of the game.
I also had problems with how the game's designer couldn't get away from his previous work at Half Life 2, as a lot of the reminiscent designs were just sticking out of the industrial-punk environment like a sore thumb.
The game also has a weird problem, where it is great at subtly telling the story through books, overheard conversations and the public speakers, but at the same time it's terrible at stringing the main plot together and making it interesting. Not to mention, the "plot twists" were telegraphed from a mile away and most of the characters were cardboard cutouts (though at the same time some of the characters were really good, so take that as you want).
Finally, the ending was just lackluster. I don't complain about it being anti-climactic, as it was expected that the "final boss" won't really be able to put up a proper resistance, but the "epilogue" felt tacked on and only explained things in very broad strokes, and it completely failed to address the two biggest issues; the Outsider's presence and his relation to Corvo at the end, and the "the world will soon end when the whales die out" point that was alluded to several times during the story.
Overall I really enjoyed the game, but I couldn't help but feel that it could have been much, much better if only it's plot-points weren't rushed and if Corvo wasn't a silent protagonist.
Oh well, I stop complaining about wasted potential now, it was still a really good game, one of the best I played this year, 8/10.