We went to Cuba (Guardalavaca, Playa Pesquero) AI a few years ago. It was a massive site with 8 restaurants (I think) and several bars, a nightclub etc. There was a main buffet restaurant where you could eat breakfast, lunch & dinner at set times (but flexible times, think each meal lasted 2-3 hours) - food there was fine, decent but not luxurious service - you got table service for drinks (wine by the glass only) but had to help yourself to everything else. There was also a 24 hour restaurant that did basic stuff like burgers, toasties and chips (possibly pizza too??) We went there for breakfast when we were off to Havana as we had an early flight and it was the only restaurant open at 5am - they made us scrambled eggs and toast I think. There was a really gross place called 'the grill' that was poolside and the food in there was - just awful. So we avoided it. Then there were dinner-only a la carte restaurants that you had to book - we went and booked for 10 nights out of the 14 on arrival and had no problems getting reservations. The food at those places was pretty good (not Le Gavroche standard, but very nice and decent quality - and wine served by the bottle, proper table service and wine coolers, same as being in any restaurant).
The only criticism I have of the restaurant set up is that all but one of the restaurants are open at the side so during the day birds are flying around and I am totally phobic about birds - so I didn't eat much during the day! In the evening they're all gone to bed so it's fine
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The hotel is on the beach and all beaches are public in Cuba, so there are locals and holidaymakers from other hotels (it's next door to the Paradisus Rio de Oro, which I believe is very lovely - we met a couple who were there on honeymoon and they said it was fantastic - also I think their restaurants are all a la carte, no buffets, think it was about 25% more expensive to go there). It's also very safe to go off the resort so we had some days out and also we went on an organised 2-day trip to Havana.
We got great service (no need to go to the bar, you will be served at your seat by the bar staff - and there's a guy with a mobile bar trolley around the pool so you don't need to even get up if you don't want to) and some great food (also some not so great, but by and large there was a ton of choice and it was fresh).
I think 5 star AI is great - but not sure I would fancy an AI with one buffet restaurant tbh. The variety is much nicer and I would personally choose local restaurants over a single buffet every meal. That is the main thing that would put me off a lot of the resorts in the Maldives - I couldn't stand 3 meals a day for a week all in the same restaurant!