I was up close and personal with one that came to a rally I was at. It was super cool and the owner REALLY liked it. He put several hundred miles on it after he rode it off the showroom floor. It looked great.
I had a new generation Ninja 250 which is supposedly slightly more powerful than the CBR 250, and it was a colossal waste of time. Acceleration was incredibly slow, vibrated and buzzed badly @ speed. I only owned it for a month. My So's Honda Reflex was faster in the hills and got 65-73 mpg AND had a trunk.
Mileage was mid 50's which was nice I suppose, but $4k can buy a lot of gas for the wing.
That being said, it was my first "sport" style bike and motivated me to get to get a Hayabusa....now THAT was a bike. It would get mid 50's if you keep it with in the speed limits. No reason to get a 250 when something like a Busa gets nearly the same mileage and has PROPER power. Used they are not much more expensive. YMMV.