Honestly, do not put too much stock in Trip Advisor reviews. They can be swayed by many different things. And as I said, SBR just finished a major renovation of all rooms in the resort and so older reviews could be still there from before the renovation.

Water temperature in December is definitely cooler than in summer. That time of year could be a problem with what they call the Christmas winds. It's often pretty windy around that time, so it could feel cooler because of that. As between those weeks, 12/9 to 12/16 would probably be less crowded on island than the week after. The weather should be about the same for both weeks.

Oh, and I forgot to say--welcome!!