Man, English anime dubs can be kind of hit-and-miss, as any anime fan knows, but ... wow. Ian Sinclair's Brook is just as good as Brook's original Japanese voice, IMO.
Makes me want to watch the dub again, actually. I've been watching the subbed version of the show and have just finished the Thriller Bark ark, which is why I decided that I wanted to hear Brook's English voice.
I must say, I am not disappointed in the least.