Just wrapped up a family vacation at the Fairmont and thought I'd post some observations that seem to differ from previous posters.
While most of my comments below will focus on the disappointments, I should be upfront that this is a very nice property, and our Beach-area casita suite was delightful. Our kids (2 and 5) had a blast, and it was certainly a wonderful--if pricey--family vacation. Given that this is a Fairmont, however, and not a major chain or all-inclusive, I was expecting a somewhat higher standard.
First, I must say I am not impressed by the restaurants. Don't get me wrong--they are perfectly fine--but nothing I'd go out of my way to dine at. Service is not particularly attentive, and certainly not up to fine-dining standards during dinner at Las Brisas, and the food is fairly mediocre. The price, as you'd expect, is not cheap, so I would hope for better. That said, we were traveling with young kids, so I would actually prefer more than one low-key restaurant. La Laguna is fine, but it gets old, especially since that's where breakfast is served.
The pools are indeed lovely, although the water in our private roof-top plunge pool was vary warm thanks to the scorching heat during the day. I was also disappointed that there is no water service at any of the pools. You are free to purchase 1.5l bottles at $10 a pop, though. No thanks! We just remembered to pack the (free) water bottles from the room.
We were well aware that our room was a long way from many of the facilities which are back towards the main property. Hence, we were looking forward to doing a lot of biking. Unfortunately, the bikes are few and far between. It is difficult to find more than one available anywhere but the main lobby, and even those you can find lying about are likely to have a broken seat or brakes. I did not ride a fully functional one the entire week. The good news is the carts are indeed frequent and friendly, so waiting for them is not an issue.
Perhaps my biggest disappointment, however, was the service. While every associate was unfailingly polite and friendly, the level of care and attention to detail from the front-line staff is not what I would have hoped for (although the management has been wonderful in dealing with several issues that arose before and during our stay). For example, I emailed our "butler" several times before arrival to make sure the room would be properly prepared for our arrival. We rolled up to the property precisely at the time I indicated we would, yet it was apparent they were scrambling to prepare our room. Housekeeping was still in it as we arrived, and they had not delivered/arranged our children's beds as we had requested, nor were there any amenities in the room. The Platinum amenity did show up after we returned from dinner, but my workout attire (specified in my profile), nor the advertised kids' goodies (stuffed animal, shampoo, etc.) never materialized.
Most frustratingly, we were informed we had a different butler (with no explanation of the change), and he was nowhere to be found on day of arrival. Indeed, I had to wander up to the concierge desk around noon the next day to have them ring him so I could begin to make arrangements for our stay. It was clear he had no knowledge of my previous requests, so we had to start from square one.
The host who escorted us to our room was very nice, and gave a perfectly pleasant tour of the property, but provided several pieces of bad advice.
1) He assured us we could proceed directly to dinner without reservation. Not true; the hostess at Las Brisas seemed somewhat taken aback that we would presume she could seat a walk-up party of four at 8pm on a Friday night, and instead suggested we return to our room and she would call later if something opened up. (Really?! With two obviously starving kids in tow? We wandered up to La Laguna instead.)
2) He suggested there were plenty of beach toys available at the beach for our kids to use. After trundling down there the following day, we discovered there are none. (You can purchase them at the Cafe by La Laguna, though.) As others have observed, the beach is fairly small, but the water is beautiful.
Also, for the gym rats, the Willow Spa fitness area is run-of-the-mill hotel standard, and certainly not high end: there are the usual array of machines, but dumbbells only go to 50lbs, and there are no free weights, pull-up/dip bars, squat racks, etc. (although there is a leg-press machine). Also of note, there is no locker/changing facility available. If you have to use the restroom, they will literally escort you to make sure you're not making use of the spa amenities. Classy.
As others have mentioned, bug spray is imperative. The swarms are so dense on our river-front balcony that the kids were actually scared to venture out in the evening hours for fear of being engulfed! They thoughtfully provide dispensers all over the property, though, so you can always refresh if you notice it wearing off.
Finally, and by far most importantly, the room TVs do not get Sky, so I was unable to watch some of the World Cup matches in the room!
To end on a positive note, let me strongly recommend the boat tours. There are two: the Fairmont tour that takes you around the property in a smaller, 6-person boat for a guided tour (reservations required; it took four days for us to get our desired time in the off season), and the Mayakoba connection, which is a hop-on, hop-off shuttle among all three resorts at Mayakoba. While the latter is intended as transportation more than leisure, we found it very sparsely used and it makes for a lovely 1:20 loop of the property. The hostess on our boat was delighted to tell us all about the flora, fauna, and property itself. We also learned that they are currently testing kayak rentals, and plan to roll those out (in addition to archery) in the coming months.