I've been to Caye Caulker 3 times and stayed in 4 different rentals. This is definitely the nicest. Clean place, nice wood floors, attractive construction, and everything you need - even a bottle of wine and 3 Belikins in the fridge. Nice! The pool is great - perfect way to cool down on a hot day. There are mosquitoes. Use the mosquito nets when you sleep, but that's pretty normal in my experience.
I like this part of the island - south side a stones throw from the airstrip. It's a 10 min walk to town, but it's nice and quiet