Seems to work
I am a big fan of Pushup Fu. It is amazing how well it works and how much it makes you want to do push ups to compete with your friends and train.
I decided to try the Lite version of Squat Fu to see what it was like and make sure it works as well as Pushup Fu. After going through the training, I can confirm that it does seem to work just about as well as the Pushup Fu app. I did have a problem at first where it kept giving me "half" warnings. I slowed down a bit and the problem stopped. I had no problems with the app counting my reps, I just had my iPhone in my pocket facing downward.
I reached the 30 rep limit of the trial app pretty effortlessly. Not sure if I am going to buy the full version or not, but I can definitely vouch for the validity and effectiveness of the app.