I actually did this from 2002-2006.
Pros: if you really do work at it for YEARS, you can get pretty good, assuming you get through that period of sucking donkey balls where everyone is hating on you because of how bad you are at the beginning. Once you are at that point 3-4 years in (after 3-4 years of DEDICATED refinement of your style, lyrical abilities, and beat-making, assuming you make your own beats) where you've started getting good, and you unleash a verbal barrage in front of chicks, they get very attracted.
Cons: once you get good, you then realize how much better you would need to be to get actually famous. Then on top of that you realize you need to get signed to a major label, which means a very distinctive voice/style and a distinctive angle the label can use to market you. Then once you realize you are 4 years in and it will probably take another 4 years to get somewhat famous, you start looking at the lifestyle famous people lead and you realize a lot of them have horrible lives where they are going crazy, getting sucked into drug problems, getting run by managers who bleed them dry, and have zero privacy in their personal lives and legions of haters everywhere. Plus girls just being attracted doesn't lay them on its own. Most girls don't even know you rap, either... it's not like you can walk around in your daily life rapping everywhere (I mean I guess you could in theory, but...).
Anyway, tl;dr, at four years in, after rapping on stages in front of crowds and having people go nuts and people telling me I was going to be on the radio/famous, I said "fuck all that noise" and signed up for a pickup bootcamp and never looked back.
Let me just tell you, it took me a lot less time to get girls from learning to pick up girls than it did from learning to rap.