I dove in vieques off of Mosquito Pier with Blackbeard Sports (the dive shop in Isabel II). I liked their guide and the process was straightforward. Nothing weird. I was a pretty new diver at the time and was diving without bringing my own dive buddy (wife isn't certified) so because of the numbers I was paired with the guide. Transportation was a van pickup at the hotel to drive to the dive site for a shore entry off of a stone jetty.
The only caution I would give is that their rental gear was weight belts rather than weight integrated into the BC. (This was 2.5 years ago , they may have upgraded since). I brought my own computer so I don't recall the details of their gauges.
Now, the good stuff: the water was fairly clear despite the winds being high that day, the dives themselves were also fun under the pier because the pickings created lots of surface area for plants to attach to and fish to hide in. They also make navigation very straightforward! The highlights for me were the sea turtles.
Vieques does have nice beaches as well, we enjoyed renting scooters to get around the island and explore, After diving, mofungo at Sabores in Isabel II will do you well.
