This game is terrible. An unmitigated cash grab. You get very, very few dances with the base purchase. And it's constantly interrupting with unavoidable ads. Essentially, you pay for the privilege of being told to buy an unlimited subscription over and over. Unlimited comes with a huge library, granted, but you never own the songs. Also, it seems like you can physically flail around and the game will still give you a perfect score? Finally, it seems impossible to know what you are doing as compared to the psychedelic on screen dancers, so improving is a major challenge (if you had to, but since you basically get a great score for existing, probably not a big deal).
Ultimately, I would pass unless you just want to get something that gives you the illusion of dancing and having a bit of fun and don't mind paying a premium for any of the actual non-teaser content.