Loved it. A few things for people to keep in mind:
1) It is not a long walk to the beach (my three and four year old did it on their own with no complaints). It's actually closer than the walk, but the sidewalk isn't a straight shot so it takes a little longer. *There is a free shuttle service that will take you to the beach if you don't want to walk*
2) The beds are generally hard, BUT are very comfortable. My mother likes soft beds, but said she oddly still loved sleeping on the beds. I slept on the pullout, and slept fine (it was a little dirty. My only criticism of the place). My two sons and their aunt and their uncle slept on the bunk beds and all four slept fine.
3) The kitchen comes with pots, pans, cups, and plates. We made several meals there of different types, and did not need anything.
4) There is a small amount of toilet paper and trash bags provided. They tell you this in the email, but in case you don't read it I'm letting you know. A Walmart and a Publix are just about a 10-15 minute drive away, so it's not hard to pick up more.
5) Besides the beach, there are a lot of other fun things to do with kids. There are a few great parks and walking trails. My father and I went running, and there was a sidewalk everywhere we ran to (almost the length of the key).
6) Pensacola is close enough that if you want to go there you can (we went Black Friday shopping), but far enough away that you aren't dealing with the lights/sounds/crowds.
7) Beach was perfect for us.
8) There is a screened-in small deck with a little table and sofa and chairs. Very comfortable and beautiful to sit on. Has a fan and a light as well.
Overall, a wonderful experience. One of the best vacation rentals I've stayed at. Price was a little more than I liked (the extra fees were the problem, not the price itself), but I was NOT disappointed.