Brac itself is a wonderful place. The diving is great. Make sure to dive the russian frigate, spectacular.
As far as Mango Manor is concerned, I have traveled extensively in the Caribbean and stayed at a variety of small hotels, resorts, and hostels. For the price (over $100/night), I was not impressed with Mango Manor.
I do want to mention however, that my stay was enjoyable but for the money there are much nicer places to stay.
I'll give you a list and you can form your own impression:
(1) After confirming my itinerary with Lynne prior to the trip, I showed up at 11pm after a long flight to to find no one at Mango Manor. Another guest was able to call Lynne and she finally showed up, telling me she thought that I was supposed to have arrived that morning.
(2) I shared my bathroom with several large spiders.
(3) There was no soap/shampoo in the shower. I ended up washing myself and my hair with handsoap from a pump bottle taken from the sink.
(4) The included "breakfast" was good but I'm a young guy and like to eat more than an egg or two and some toast for breakfast. I immediately had to go over to the nearby grocery to find more food.
(5) The general attitude of the owners was friendly but I couldn't help but feel that they were...not sure how to describe this...talking down to me ever so slightly. I didn't feel they were genuine.
(6) I would like to add that I went over to the dive shop at the Brac Reef hotel the first morning to get some recommendations for dive sites around the island (They're the only dive operator on the island? i think). The dive shop staff was overly helpful and extremely friendly. They have some great advice and will be able to tell you about sites where the bouy markers have been washed away.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC