First off, owner was a treat to work with.
The Grand Mayan is a luxury resort with all the perks you would expect: restaurants, concierge, spa, golf, room-service etc. What we enjoyed most however, was the flexibility the accommodations afforded our family: a huge room (two bedrooms + living room and kitchenette), proximity to the beach, and water activities for the kids. We totally feel like we "scored" on this vacation.
This is a time-share place. Knowing that, we opted to not listen to the high-intensity sales pitch (foregoing out discount), but our friends who were there have done it and claim it was one of the pushiest they've ever had to endure. Be warned.
The rooms have A/C (a blessing for that part of Mexico). The kitchens do NOT have ovens though - making large meals a little more burdensome to come up with. Housekeeping will make up the sofa-beds in the evening on your request. Towels for the room abound. The deck is MAGNIFICENT! Perfect views and get this... your own plunge pool. Our kids LOVED this part of the stay.
The beach was combed and clean. Even at 100% capacity, we did not feel crowded at this resort, there was always plenty of space, and plenty of help available. English was spoken by almost everyone working there as well, making communication super easy.
The water park that used to be outside the door has moved down the street to a neighboring Mayan property, and is accessible by free shuttle. I highly recommend checking it out - even if you don't have kids (who will love it) the Lazy River is a nice relaxing time.