The other reviews are short, but pretty descriptive as to what you get at this place. The houses (La Mer is one and Dewey is two) are part of a bigger collection owned by southernmost and there are two or three actual hotels on the property (I would consider La Mer and Dewey house more of a B&B). What this does is gives you the amenities of a larger operation with the feel of an actual B&B. There were three pools, one hot tub, a tiki bar, a poolside bar, a beach and a beach cafe/bar. Across the street was an ice cream stand, a souvenir shop and a convenience store. In the hotel across a parking lot was a fitness center.
Some quick hits about the property and amenities: the beach has seaweed and the ocean right here is rocky, but still nice to have the beach and sand right outside your door, go to the concierge stand to get 2 for 1 drink tickets for Duval St., free wi-fi, beer is reasonably priced and mixed drinks are expensive at the tiki and poolside bars, house location is at the south end of Duval St and not in the thick of things, but close enough to get there...but a long walk if you want to go all the way to the N side of duval (Relatively speaking, the island is only 2m X 4m), spa looked small and only there to say they had a spa (but I never tried it), free continental breakfast (cereal, hard boiled eggs, pastries, belgium waffles, english muffins, bread, etc).
We rented a scooter and it was well worth it ($150/3 days) as scooter parking was plentiful and car parking was not. The beach at the state park is worth the visit and easy to get to via scooter (or car).
The houses have a total of 19 rooms that come with a safe, umbrella, wine glasses, martini glasses, refrigerators, coffee makers and robes in each room.