Dark Messiah - First Impressions @ GameSpy, IGN & IGN AU

Three sets of first impressions for Dark Messiah are up across the IGNSpy network.  Let's start with GameSpy, who note "We're a little bit disappointed with the single-player game":

The game's designers have very cannily exploited the Source Engine to provide you with a multitude of wicked ways to dispatch your enemies. Melee combat is brutal and visceral, and when it's at its best, it's immensely gratifying. When you land your blows, they feel solid and full of impact. Combat is at its most interesting, however, when you're enouraged to indulge in the interplay between physical, magical, and environmental attacks. In one example, you can set a barrel on fire, hurl it into a group of unsuspecting guards via telekinesis, and watch the mania ensue. There are plenty of elements in the environments that you can use in combat, and in many cases, exploiting them is the best way to surmount unfavorable odds. Nitty-gritty melee combat, while explosive and satisfying, sometimes feels frustratingly fast and loose, and the enemy AI is a bit catatonic at times. Don't be surprised to put an arrow between a guard's eyes only to have his neighbor stare at his corpse for 30 seconds before responding.

...next to IGN:

Even with all this differing options for combat, we still found ourselves growing bored around halfway through the game. At this point you'll have seen all the tricks the game has to offer, like punting enemies off cliffs and causing statues or barrels to crash down on their heads by knocking out support beams. You'll also start to see the large bosses of the game start repeating. The first time you fight a Cyclops or Pao-Kai, you'll definitely be taken aback by their size and power. However, by the fourth Cyclops and third Pao-Kai it's not so impressive anymore. You'll also start to notice how some aspects of the game are largely exploitable. Setting a barrel on fire and holding onto it instead of firing it with telekinesis basically acts as an instant kill for any enemy you touch. All you have to do is pick up the container, set it ablaze, lightly touch any nearby enemies before it goes out, and watch all your foes burn to death.

...and finally, IGN Australia:

Puzzles-wise, many of the game's more thoughtful and interesting moments are cleverly scripted for moments of key tension and exhilaration. A rooftop chase sequence early in the game is fast and just precarious enough to be genuinely thrilling. In pursuing a scurrying Gollum-like creature in pursuit of a key quest item, you have mere moments to scramble across awnings and through open windows in a deft combination of platforming skills and problem-solving. Branching paths are minimal, however; you're more likely to find yourself taking a jump onto a board that splinters and send you plummeting to the unforgiving soil below, forcing a rethink of your approach and cautious footwork. Autosaving is very well implemented too - saving at key moments to avoid bouts of severe frustration at having to redo a load of do-or-die leaps of faith.