I've not stayed there, but did visit the place just before it opened, knew some of the staff. It's a very nice setup, with rooms on the hill above, some overlooking the strait. Everything seems well appointed. The location is a good as any, and most dive sites are very close by. There are rather a number of steps from the beach to the top, something I'm not fond of, but cannot think of other negatives. I'd be surprised if it was not well run, with good guides, boats, food.
This will be my fifth consecutive year going to Lembeh, and I'll be further along, at Bastianos, from the end of Aug for three weeks. On my last trip, in Jan [Bastianos], one of the guides said that business wasn't going to well at Black Sand, but I don't consider this to be a negative. The place is still relatively new, and not exactly cheap. Being less known, that's probably why they have space. I'm not able to negotiate steps that well, and that's the only reason I have for not going there.
There have been a couple photo shootouts there the past year or so, and you might try scanning the photo forum to find someone with more detail.
I assume you will be there Aug or Sep. No one is overly busy from Oct on, until Late Dec, when Asian flights are cheap, and people have lots of time off.
If you've not been to Lembeh before, and need more info, I'm
kc@kilili.com.