FWIW, the White Manta did two trips to this destination this year. We may schedule future trips but not likely in 2014. Other than the people on our boat, the only other divers we saw underwater were at the Maratua channel. They were swimming off as we came in so this is definitely not a crowded area. The highlight od the trip was definitely this channel. The school of barracuda there were the biggest, densest school I have ever seen of any species. It put the jacks and barracuda at Sipadan to shame. I never managed to get into the middle of them but we often swam inches away underneath of them. Also spotted there were quite a few reef sharks, turtles and a whaleshark. Snorkeling at Kakaban's jellyfish lake was awesome as well. The reefs at Sangalaki were in quite good shape but we only managed to see one manta which used to be plentiful. Macro life at all reefs was very good, but not excellent. We also stopped at Derawan were the jetty provided excellent macro diving without moving far at all. As Frogfish put it, the diving in that area is very good but not better than Komodo, Rajah Ampat or the Banda Sea. Then again, the lack of other divers may make it worth the trip for you.
And if anyone is looking for these desinations, they are in Indonesia, rather than Malaysia. Not sure why the post was made here.
