Similar to Deus Ex? No, I wouldn't say that. Apart from having an inventory and skills, there are no similarities whatsoever. Dark Messiah is a straight first person slasher with light RPG elements (skills, inventory, skill requirements for some items) and as such it's fairly linear. At the end, you can make a choice between following either the demon chick or the annoying mage chick and there are different endings - I think there are four in total - but other than that, it's linear and I don't see how anyone could associate it with Deus Ex. What it does have are secret areas within the level, as in the shooters of old.
What DM does great, however, is the combat and the way all classes play differently. Melee combat is great and feels very satisfying, and kicking is fun albeit overpowered (kicking enemies into sharp stakes at the wall or down a cliff is an insta-kill). I haven't played as an archer or a mage, but from what I've heard, they're very satisfying to play, too - the mage especially, with some spells that can affect the environment (setting fire to oil, for example). Playing around with the physics is fun, too.
While the story is alright, too, it's mostly a game you play for the combat, and the combat alone. It's definitely worth checking out, but don't expect it to be anything like Deus Ex, that will only end in disappointment. Expect to get a great action game, and you will have fun.
