I have nothing to say against the violence because it emphasizes the brutality of the captain to a point that I find it actually believable. In my opinion, dulling the brutality would have made it far more 'cartoon-like' because it would have certainly left me in limbo about the captain, as he seems to be almost benign on the other hand when he is in the company of his family and the doctor. Then he suddenly transforms into a brutal monster and it's a jarring contrast to his otherwise almost admirable demeanor (such as a man in his profession is expected to maintain.)
If his evil side had been left to my imagination or the imagination of a lesser director than del Toro, I would not have felt so completely repulsed by such an evil character. Anyway... I didn't enjoy the flick. In part, it's because I was expecting more of this fantasy world, but mostly I found myself not enjoying it because I was completely unable to relate to both the story and the characters.
The setting was obscure, albeit unique... and the characters were too desolate to engage me and interest me. I saw Letters to Iwo Jima, another war movie, a few days later, and it deepened my regret for seeing Pan's Labyrinth as that film was just as brutal, but in two hours it still managed to provide me with characters who, although just as desolate as those in Pan's Labyrinth, had a depth that shined through and kept me emotionally invested in their fates till the end.
In conclusion, Pan's Labyrinth succeeded at being a visual feast but completely bombed at providing a single character to whom the audience could feel attached because it was too busy jumping between the real world and a completely redundant fantasy world. It's such an accurate portrayal of what might have been that it's just plain boring.