I had a couple of stays here over the last few weeks. I would probably go back if it weren't sold out for my next time in Fiji. I was by myself and the hotel is clearly a romantic/ family (more on that later) resort of the type that I usually avoid, so please take any criticisms along those lines from me with a pinch of salt. It was also Easter holiday season in Australia, and it seems that Australian kids are REALLY REALLY LOUD and more disruptive than I'm used to from other cultures, so that was a factor.

What's interesting about the resort is that it manages to combine a number of different experiences in both accommodation and F&B, which I'll outline below:

Accommodation:
I'd separate the resort into three very distinct types of accommodation. Firstly, the basic rooms are fine, but in long blocks with a bit of a dorm feel. They're a bit on the small side and the ones near the main pools will be INCREDIBLY LOUD if you're around at an Australian holiday period - make sure to avoid unless you want to use the pool with young kids. Secondly, you have the bures on the beach/ ocean. They're mainly duplexes and look quite nice - either with a beach at their feet or a view into the ocean. Lastly, the overwater Bures are adults only and quite nice. They're large and of a design mixing modern hotel style with Fijian style in a way which wouldn't be out of place in a proper luxury hotel. They are peaceful (with the exception of shouting American honeymooners) and have direct water access into the lagoon. I didn't much like the lagoon - I think the resort needs to recruit a marine biologist. The water was slightly muddy (sand from the beach) and had a bit of a problem with algae (nothing too drastic). I would not stay here for a honeymoon and would not pay $800+US a night, but as an SNA upgrade (cleared twice, once despite no availability online) it is exceptional

F&B/ Resort:
Similar to the accommodation, the resort has some very different F&B options. Some thoughts:
Overall: The resort is quite pretty, though obviously not the fully thatch authentic look you get in ether 3* eco-resorts or in true luxury properties. At night in particular it is very attractive - they've done a good job on the lighting.
Breakfast: Breakfast is served in Goji and has a large buffet of the sort you would expect at a family resort hotel. Really not my style, but breadth was strong and quality adequate. As a single person I had my table given away a couple of times while getting up to get food which is a bit irritating, so I learnt to bring random stuff to defend my table. As mentioned, the Aussie children were LOUD and run around the place knocking into people, throwing stuff on the floor, etc. and so breakfast was not an especially peaceful experience.
Pools: The two main pools are next to each other and have a swim-up bar. Both the children's pool and the normal pool were swamped with children to the degree that I wasn't able to sit at the swim-up bar without getting inflatable things thrown at me, children jumping onto the bar by my drink, throwing water over me, etc. Overall though they looked ok and were in good condition. There were "activate" style entertainers leading sessions of the limbo, water aerobics, etc. Fair to say this was not really "me".
Fish Bar: I found the adults-only pool and restaurant area on my third day. Not only was it very peaceful, but I also thought it was quite beautiful (and infinity pool over the ocean) and with notably higher quality fresh food than in elsewhere in the resort. There were relatively few couples without children (mainly American) and so it was quite social. I really enjoyed this part of the hotel and would go back for another afternoon here
Other venues: I didn't spend a lot of time anywhere else, as I tended to eat a lot of my meals in my bure. Room service was acceptable, but not especially nice. There is live music at the main bar in the evenings (along with a host of resort activities) and one evening there was a Fijian singer who was exceptionally good. I hear a lot of live music at hotels, and apart from the SGS in Bangkok, you don't often come across anyone particularly interesting

Service overall was solid, obviously bearing in mind some speed considerations to the region which others have noted. The hotel didn't know how to deal with a Your24 request (I rarely get compliance nowadays, so won't blame them) and sort of screwed up with the compromise which was a bit annoying. I had to wait around in my Bure for 45min waiting for transport which then took me to a room occupied by someone else, leading me to then wait another 20min until they found a basic room which was free. That aside though, service was reliable throughout.

The mainland of Fiji has a lot of hotels, and for the price the Marriott Fiji Momi May is a convenient and competent hotel, even if not one that you'll never forget. It's about 10% more expensive than the Sheraton and the Westin in Denaru which I expect to be a lot worse(but is another 30min further by cab ride) - I'll find out next week after I stay at the Westin.