I haven't been to Antigua, but checked the most recent issue of Undercurrent for diver reviews. The only things I came across were disparaging comments about the diving in general (no specifics) and that you shouldn't go out with the boats that cater to the cruise ships because they only go to the near-shore reefs.
I'd search the internet and e-mail various shops with your questions. I've done this with great success on dive trips to Mexico, Australia and Hawaii. Include questions like: Radio and oxygen on board? Divemaster in the water? Free to dive your own plan or strictly follow-the-leader? What size tanks.. I got stuck with 60's once and a whole group of newbies that only had 35 min bottom time on a 40' profile as a result! I figure that if a shop doesn't bother to respond to an e-mail inquiry, they shouldn't get my business.