only book it if u really going to use the spa extensively , eat a lot and make use of the water activities.
food is not cheap and dinner buffet is around 100USD pp. It depends on the rate u get and what the base rate is. I wouldnt book it all days as u certainly just wanna relax some time only...
This isn't just buffet though it is all restaurants what isn't clear is whether it is anything you want in terms of food and drink or a restricted selection. It seems like superb value to me though, based on normal Maldives prices