What kind of performance can I expect from a Ninja 250?

It's a really light bike and handles like a dream. It will out-accelerate all but the most expensive sports cars... But it's also a great beginner bike because the power doesn't come until 8k RPM, so it won't intimidate a beginner. Power is plentiful from 9k all the way up to the 14k redline (peak hp is at 12,500); if you manipulate the 6 speed gearbox properly you will rarely lack for acceleration... Of the "budget" 250s available in the US market, the Ninja 250 is by far the best choice.