This is a great park on a barrier island just on the other side of St. Augustine, Florida. I went to college in St. Augustine and spent time at this state park during the day while there. I camped there once while in college but recently revisited the area and stayed here once again.
The park is relatively large and full of people most of the year. I had to wait quite a while to check in, as there was a long line of RVs in front of me. That being said, the sites are nicely spread out and wooded (set back a bit from the beach itself). The beach is a short walk from the sites and is a great place to watch the sunrise.
The facilities are clean and there's a lot happening there. There's a rather large camp store and there was a night of live music happening at one of the pavilions while we stayed there. The campground is also close to the amphitheater and we got to fall asleep to an O.A.R. concert which was actually quite awesome. We got a free concert!
We visited in the fall and the temperature and mosquitos were tolerable. As others have said, the town of St. Augustine is close by (just a short drive over the historic Bridge of Lions) but you can also find everything you need just down the road on the island itself.