Im on week 3 and already see an increase in strength and slimming of the thighs. I do my squats with a Swiss ball between me and the wall. I find this stabilizes my form better and feel less afraid of my knees going out.
My only suggestion would be to give people new to squatting that option. Place a diagram showing them this option with a ball with the other diagram.
Also, make the daily routine numbers bigger - not the screens with the individual number and timer but the opening page you open for that day with the initial routine listed horizontally. I like to see what I have tovdo before I start and its TOO small.
From a marketing perspective, you would probably sell more of this application if you added a similar application targeting women and called it "slimming thighs."
Great app! Thanks!
Dr SO about Two Hundred Squats: Strengthen Your Lower Body