Saw this on both Saturday and Sunday with different people, and really enjoyed it both times... will probably pick it up on DVD as well! Haven't read the comics though, so I can't really make any source material comparisons.
Overall agree with the posts above... very gory, but in a fairly comic fashion... there was nothing that was gruesome in the same way as you'd expect from, say, a horror movie or something. There was nothing incredible about it, but it was a good movie all round, managing to keep comedy, action and some drama in a fairly decent balance.
But then I'm a sucker for seeing anything at the cinema so I could be completely wrong.