Spent 4 days in Lembeh last month. Enjoyed the diving. Got great service and guided diving from Divers Lodge in Lembeh. Very nice accomodation, good food and interesting guests. Mostly European guests, but another Canadian was there when I was there as well. Lots of interesting creatures, others who have stayed longer will likely give you better info but I would go back.
Highlights were seahorses, mandrin fish and the dive at a site called Angels Window - or something like that. Nudibranchs everywhere. Could easily have spent another week. Wish my camera had arrived with me instead of two days later.
Indonesian domestic airlines are the worst I have ever travelled on. In four flights within Indonesia only one was on time - ie only 30 minutes late. The others were all at least 5 hours late leaving. Leave lots and lots of time for connections.
A client that does class action law and specializes in aircraft issues tells me that it is almost to the point where they can't get insurance any more. One of, if not the worst safety records on the planet. Having said that the staff were always polite and worked very hard to make everything work as well as possible.