It's free; why not just try it?
Although a caveat: if you have to ask about it, maybe it's not for you. It allows you to change many parameters of common applications in your Mac. Most can be accessed other ways, this application just makes it easier. So the inexperienced user can get themselves a messed up Mac if they aren't careful. Unlikely it would brick your machine, of course, but be careful.
It is by the same developer that does Onyx, which has been a helpful application on the Mac for like forever.
