I was there at the end of November / early December last year. I thought that the diving was great, although at the time I didn't have much to compare it with. I did the resort course and then a couple of dives the next day with a small group -- there were only three of us diving plus the DM and some friends just along for the ride. The DM - Alex - kept a close eye on me and everything went very well. I've since gone on and got my OW certification. Along the way we saw a lot of sealife: whales, dolphins and rays -- Bandaras Bay seem really good for that.
Hope you have a good trip.
