Overall we really enjoyed our stay at Quinta Del Sol. The condo was clean and quiet, and had all the advertised amenities. The kids had a great time playing in the pools and at the very quiet beach next to the property. There is some decent snorkelling very close by, I saw plenty of fish and some small skates. Puerto Aventuras is conveniently located for going to Tulum, Akumal, Playa del Carmen or for visiting one of the nearby theme parks (we went to Xel-ha, which the kids loved). Jane the owner was very friendly and helpful, and the building is well managed and the staff were all very nice.
Our party was two families with four adults and three children and the space was very comfortable for that many people. One of the bedrooms is quite small, but the other two are large and comfortable. The beds were all firm and comfortable to sleep on, which is a rarity in my experience of rental properties. We didn't sleep on the sofa bed, but you kind of know what to expect with those... ;-) We had a bit of trouble with the air conditioning in the small room, but we talked to the building manager and he got it sorted out.
The kitchen is not large, but it's well stocked with pots, pans, cooking utensils, plates, cups and all the bits and pieces we needed to make meals for our party. We found two cooks could get by in the kitchen with some bumping, but three was too many. :) The appliances are all new and worked great, though we did have trouble finding dishwashing detergent at the local grocery store. The closest large grocery store is a 20-30 minute walk (without kids), or a short taxi ride.
We had one very tasty dinner at Dos Chiles in Puerto Aventuras, and made several trips to town for Jessie's Gelato (very good!) The town is touristy, but lively at night with lots of live music and lots of people out and about. We didn't check out the dolphin or other marine shows in town, so no comment there.
The only complaint we really had with the condo was that the Internet is *very* spotty. We had difficultly getting a Wifi signal through most of the condo - the most reliable spots seemed to be near or on the balcony. On top of that, during peak times (7-10pm) the Internet is *unbearably* slow. It's a shared connection with a number of other units, so when everybody is surfing, nobody is going anywhere.