All we are saying that he may be brutal in some way but overall he is a terrible fighter. He doesn't have any skills all he has is a large amount of chakra which he does not control sometimes. And if you really want to compare him with someone brutal then lets compare him to Orochimaru. Orochimaru may not have started out as young as Gaara but he has done things far worse than anyone else. We don't even know half of what he has done. But what can be worse than taking the body of another.