Well I just got back this past weekend, and I have to say, I had a great time. The location of the Aquarium resort was pretty awesome, right on (or in) the water. The rooms were in separate "pods" so to speak, that had about 15 rooms in each pod, and were located virtually in the water. No beach on the resort, but I was there to dive anyway, not sit in the sand. There was a nice beach in easy walking distance if that was something a spouse would enjoy. The locals didn't speak great english overall, but they were generally very friendly. It's a safe place, we would go out walking the town at night on a regular basis with no issues. Overall the resort was nice, but not "5 star".
The diving was fantastic. I did 11 dives, saw a great assortment of marine life, some massive puffer fish, lots of stingrays, insane amounts of colour. My only other tropical comparison would be Cuba, and San Andres beats Cuba hand down. We saw a couple small nurse sharks, and some octopus'. Our dive leader told us that there was a chance of seeing blacktip reef sharks on the blue wall, and he brought a noise maker to try to attract them, but with a group of 9 divers, he didn't expect to have much luck, and we didn't.
Overall, I had a great time and I would definetly go back again.
Jim