This is a classic exercise for the inner area of the chest. It's an exercise that you should do if you're on a definition or workout cycle. It will not build muscle mass. Thus, if your goal is to put on slabs of muscle onto your chest you should select other dumbbell exercises that involve the use of heavier dumbbells and different types of movement (press).
This exercise is a great exercise for women because it frames the chest making it look more defined and firm(er). For guys, this exercise will give the chest a more defined and chiseled look that creates visible "chest plates", the kind found on superheros!
It's also worth pointing out that this exercise is more effective if you have a spotter behind you that is there to help you push yourself to almost complete failure. Doing this increases the overall effect that this exercise has on your chest. Simply put, it's more bang for your energy invested. If you don't have a spotter you can't go all out on each set you perform.