I've been using ofoto for printing images from my camera. They do an OK job but they overprocess - I see unsharp mask damage. I'm ready to try another printer.
I haven't found a good review site, but looking around I did find PrintRoom.com. Their prices are better than ofoto, you can tell them not to do any enhancements, they have a FAQ for pro photographers, and they even provide an ICC profile if you want to colour match yourself. Worth a shot.