This is a simple exercise and somewhat underestimated. It does wonders for the chest muscles and the best thing is that it can be done anywhere.
You can do variations on this exercise by simply doing it with narrow (to target your inner chest muscles) or wide grip (to target outer portions of your pectorals.
One thing to point out is that this exercise is not an exercise that you should base your entire chest workout around. This exercise should be treated as an addition meaning that you will construct your chest workout around more traditional high-yield chest exercises and you will simply do this exercise as a 3rd or 4th exercise. As good as this exercise is, it is by no means a substitute for the big daddy of chest exercises - the traditional bench press!