Anyways, the full walkthrough's going to be delayed slightly because I've been having trouble getting my venues to show in the bin, so I can't show the breakdown of it just yet. I can however, give you a sneak peak of the dance floor, which happens to fit quite nicely in the gym from Sunset Valley (I don't know why but it's always been my favourite).
In the meantime, I also have some footage of the ballet bar. When you click on it you get the options to 'Warm Up', 'Exercise' or 'Train' if your Sim is at a high enough level. I haven't gotten a sim to that point yet but I'd presume at this point it's like how training works for exercise equipment.
Using the bar to train will also teach your sims how to Plie, Pirouette and finally Echappe. I found they learned these skills at a faster rate than going to ballet class as children, and even if your sim is a teen (or older). It's implied that you can also show off the moves, but either I've run into a glitch or I need a sim to be at the right friendship level to perform the interaction. I'm not sure yet.
When my venues get sorted out, I'll take some more screenshots and put up the official review. This is also going to include the new windows and the public showers.