This is definitely not a waste of time. I do routines similar to this and I've definitely gotten stronger doing them. I also do many pull-ups as well which aren't on this chart, but all of these exercises are great exercises. You are NOT going to lose a lot of weight with this alone. However, if you are already a healthy active person then adding a routing like this only helps.

My brother spends at least 5 days a week at a gym lifting weights and eats a very strict diet. I'm more of the runner type, doing Taekwondo 2 days a week and more body weight workouts like this (and I eat fairly well for the most part). He's definitely stronger than me, but I have no doubt that I'm in just as good of shape if not better than him.