I watched Avalon when it was first released (before it had subtitles or a dub) and was so enthralled that I watched the sub'd then the dub'd versions when they came out too. Yes, it's a bit slow, but I think that added to the atmosphere. I loved it. Anyone who didn't mind the pacing of Ghost in the Shell 2: Innocence would probably like this too.
Kenji Kawai, who created the soundtrack is, to me, the Japanese Danny Elfman (who, again, to me, has been phoning it in for several years now.)
Some might call it a Matrix ripoff, but since The Matrix was inspired by other anime in this genre, that would be a superficial criticism.