Curse of Darkness' voice acting is pretty great across the board, though I suppose Julia is arguable. I kind of didn't mind her hokey delivery, though I admit it's there.
Lament's? Err, I think Walter is really powerfully done. I love how theatrical and melodramatic he is. Rinaldo and Medusa are cool, too, but everyone else? I wasn't especially impressed. Leon and Sara are disappointing, I feel. Sara's too unrealistic (without being cool like Walter), and Leon just doesn't have much power behind him, which is especially disappointing considering the situations he finds himself in. Death doesn't have nearly the personality he had in Symphony of the Night. Mathias is fine.
I prefer the Curse of Darkness soundtrack, myself. There's more variety and it's more exciting. It has more muscle behind it without sacrificing grace or style.