I've been bartending for 6 years now. Bartending school is a complete waste of money. You will probably need to start out at a hole in the wall or barback to get experience and move up. If you are a guy, you have to be fast to make money. If you're a girl, just flirt and invest in some fake boobs. Seriously.
I've done it for a while now so there's not really much that suprises me anymore. It also totally depends on the type of place you bartend. Hotel, Nightclub, Biker Bar, Restaurant, etc. I've always worked at a club so I deal with douches, lots and lots of douches. You just have to try and not let it get to you, because it probably will at first. People treat you like crap if you're in the service industry a lot of times.
That said, there are a ton of great aspects. You HAVE to work with cool people, if I didn't have that I would've quit a long time ago. Over time you will get your "regulars". The people that consistently come in help you pass the time and tip you very well.
Think about it and realize you will probably have to give up the vast majority of your weekends. If that doesn't bother you then by all means start looking and get your bar card. I work two nights a week and probably clear $20 K a year. That's not especially high either, the girls clear a lot more than that and don't have to be very good.
Good luck.