The trip was well coordinated and the scenery was perfect. The boat was a little older and not the fanciest, but the crew was fantastic. Mosquito, the main guide, was excellent, and he perfectly switched from Spanish to English in all of his descriptions and instructions.
Mosquito did an excellent job during the snorkeling portion of the trip. I was with two children (8 & 10 y/o) who are medium-skilled swimmers, and 25 minutes of paddling around in the open sea was a lot for them. That said, Mosquito made sure that they were accounted for and he encouraged them to use the floating ring as he towed them around when they got tired or had issues with the equipment.
The food at Isla Mujeres was mediocre, but plentiful. The staff again were very friendly. Drinks were somewhat weak, but this is generally my experience in these types of "all inclusive" tours.
The town in Isla Mujeres is a bit of a tourist trap right where the pier is (as expected), but if you get off the main drag and walk a bit further in, it is quieter and you can find a few really nice spots to stop and have a margarita or tequila. The kids loved the beach there, though it was crowded.
Overall, it was a lovely experience, and would recommend it for families. Make sure to bring plenty of biodegradable sunscreen - there isn't always a ton of shade on the boat, and it depends on where you sit and which way the boat is pointing in any given moment.