I have been to Pleasure Island but not stayed there. Nice, kind of basic but clean, individual cabanas on the beach. Good food at the restaurant, friendly folks who run it and work there. Very quiet island. Only one other hotel/restaurant. Mainly private houses. There is a very cool aquarium on the island definitely worth a visit. I snorkeled around the island but did not fish there. There are lots of pics of it on my photo site on the Sept 04 trip page.
http://photos.yahoo.com/barbsbelize

www.barbsbelize.com