Is eXtreme Power Supply Calculator Pro any good?

I was talking to some friend the other days, about computer, and one of them mentioned Extreme Power Supply Calculator Pro.
Now, I didn't knew anything about this software, so I've done some research, but still can't figure if it is good for a computer or not.
Can you please explain to me, what are its features, and if it is good.
Basically what does it do for my computer?
