I used to find this name ugly and repulsive, but now that I'm a little older, and have read the Harry Potter series, I've come to really like it. I like the sound of it, and it looks good on paper. But, I think I'm at least partially influenced by the fantastic Neville Longbottom!
It makes me think of "nevus" (a mole) and "snivel," two fairly repulsive words. Then, if one remembers that it is a surname used as a given name (wrong) and that it was the name of conscriptor, i.e. slaver, and Nazi-appeaser Neville Chamberlain, one can see the negative connotations outweigh any positive Harry Potter ones.