Really good adaptation, but I'm surprised (and pleased) that the mangaka has such a "straight" approach. Most adaptations get re-styled to look like mainstream manga. I think this shows his talent more, and respects the original material.
On the other hand, H.P.L. was a sad, twisted, man. He hated humanity, and meant to depict almost everyone as somewhat disgusting. The artist could certainly turn up the ugly a notch or two.