Dark Messiah is a light, fun action RPG, but has several potentially fatal bugs.
However, this release for the 360 starts a solid action RPG. They've fixed most of the bugs from the PC edition, and it provides a reasonable action RPG experience. Don't go in expecting either Oblivion on the RPG end, or Half-life on the first-person action game end. This game accomplishes what it's trying to be: a simple, light, hack-n-slash, loot-grabbing "dungeon crawler".
The visuals are pretty dated, but workable. Sounds and music are both well done, though neither is cutting-edge. NPC AI is not great, but workable.
The real problem are some fatal bugs. A few levels have a 50/50 chance of starting with you dead (before you even get to move, ending the game), or allow you to get "stuck" where you cannot proceed. These types of bugs are really unforgivable on console games -- there's no way to correct these problems.
The good:
* Easy to jump into and play, lots of basic platforming, lots of little hidden goodies to locate in the game world
* Generally solid -- I haven't experienced any of the graphical frame rate issues mentioned in some reviews
The bad:
* Fatal bugs... this is a killer....
* VERY lightweight -- to call it an "RPG" is more to do so because it's a swords-and-sorcery game than because it's really trying to be "role playing".
* Enemy AI is weak