Leather grips have a different feel to them that is liked by some, but not by others. It adds weight to the handle. I wouldn't say there is any "real benefits" to a leather grip other than the different feel and weight to the handle. If you've never used one, you should try it and see if you like it.
Playing in the Open! PK Copper Ace, Gut/Poly. Give me a racquet and I'll find a way to win!