Granted, there is no subsitute for squats with a barbell, but it's always good to mix things up. My gym got this machine in the last year, and it's my favorite for squat alternatives. You stand facing the blue pad for a squat movement, stand with your back to the blue pad for a hack squat. When I use this, I do three warmup sets, four heavy work sets, and a final set with low weight, high reps (25 or so).