My wife and I were there 4 years ago. We stayed at a huge A/I, the Grand Palladium. Not in Tulum but on the Mayan Riviera not very far from there. We had a great time, mostly because we spent little time at the resort. It was very easy to jump in a collectivo (taxi van) and travel up and down the coast. We spent time in Playa del Carmen to the north as far as Tulum to the south. If you enjoy snorkeling don't miss out on Xel-Ha. Its a huge lagoon full of big fish. Water is brackish so a little cool and not super clear but I loved it there. Spent around 6 hours in the water checking out the monster size parrot fish and other biggies.
There is a really sweet beach hidden away behind the ruins at Tulum.
I guess the only negative thing I can think of is that I got the infamous stomach issue while there which has never happened anywhere else except a light case in Cuba. For a day or so I never ventured far from a toilet.