I have a 250
DONT get it if you have enough experience with riding bikes. Go for a 500cc ninja, or for, the very most, a 650.
The toughest thing for you should be adapting to corners, they are a lot different on a street bike with sticky tires. NEVER hit the front brake, or you might highside! And always let the clutch out as smooth as possible, or powrshift during a corner if you are accerlerating, or decellerating though it (not normal, try and maintain a constant speed thorough corners)
Yeah, i had a 250 for my 2nd bike, and, the only time i dropped it was because of the front brakes! I was used to drum brakes, which have a lot less stopping power. I locked up the front and highsided.
Powerwise, and handling wise, it is way to forgiving,
If you want performance, get a 500,(or 600-650) and don't push it.
If you want economy, get a 250!