There are 5 different dance pads on the mat and you have to step on the right pad when its coloured light flashes. It has the songs from HSM 3 and while it certainly doesn't teach you fancy dance routines, my 7 year old daughter and her friends love it. At the end of the song it gives you a score out of 100.
Aged 7 she has now mastered the lowest level for each song and is working her way up the next level. So I would guess it would be best for 4-9 year olds. Her 3 1/2 year old brother also loves it and has a go whenever allowed.