Nirwana Resort Hotel is fine, just do it.
Overall i had a great time at this resort. The rooms were reasonable, and the staff were very friendly. The beds are also very comfortable. Food was good and the prices fair. The buffet breakfast is also very nice.
the pool is huge and very
... relaxing. Can be a bit hard to find a lounge chair and also towels can get rare later in the day. The swim up bar though is great and the prices are fairly reasonable (once you're used to singapore drink prices everything seems reasonable though).
the mini-mart though is unbelievably expensive, $5 for 1. 25 litres of coke zero and $25 or so for sunscreen (which you will need).
tried the snorkelling at the beach resort nearby which i wouldn't recommend, not much to see, but maybe the tour version is better. Also the night club type of thing they have here was quite dead at night. Maybe try silk next time. The whole place doesn't seem like much of a partying place to me.
book yourself a massage at one of the places outside of the resort and get yourself a cool fake tattoo afterwards. Recommended.