My wife and I were there in late March with our then 6 year old son. We loved it! The weather was great and the resort when phenominal.
The beach was great, not to crowded. It's actually a small protected cove. You can paddle board and snorkel, but not surf.
The spa looked fun, my wife and I took a very short tour of it.
Rainbow Reef was good, but could get boring if you did it multiple times. It's not that big.
The food was good and they are really trying to bring the price down to make it more affordable.
All that being said, without knowing what you want do on the island, I don't know if I can recommend it for you. The main drawback is that it's not next to any of the major tourist places; North Shore, Waikiki, Diamond Head, etc. All of those will be at least a 30 minute drive.
If you want to spend most of your time at the resort or are ok with driving then I would easily recommend it. If you don't want to drive a lot and still see the major sites, than I would be hesitant to recommend it.