I just returned from staying on Mabul at Borneo Divers. While it is a newer resort and the landscaping may not be as nice as the older SMART Resort, I found the employees and food to be wonderful. Mabul is a very small island and it only takes about 20 minutes to walk around the whole island. The island has three resorts and two villages. SMART resort (Sipidan Mabul resort) was very pretty with big palm trees and nice landscaping. When we dropped in for a drink, however, we were met with less than friendly employees. Sipidan Water Village was also very scenic. I understand that it is a bit pricier than the others. I only made a brief visit there.
The two villages were very different from each other. One was a typical fishing village built on stilts over the water. The other was a Sea Gypsy village. It was much more "basic" than the other as these people are very nomadic and, for the most part, live on their boats.
Borneo Divers is where I stayed. After a visit to last years DEMA, we took advantage of a special they were running. Airfare from Newark, NJ, six days of three dives a day(two on Sipidan and one on either Mabul or Kopalai), all lodging and meals, great guides who picked us up from all airports and gave us city tours, ALL FOR 2,200.00 US!! A great deal!
The resort was quite nice and the employees were exceptionally nice. One day I was ill, and the manager brought me medications and food/drink. Very nice. I can't say enough nice things about how well we were treated.
I could not have gone to many places in the Caribbean for that cheap. Contact Borneo Divers directly and you might just get a super deal too.