I did not have ninja as an option as i was looking at benelli 600i but it was but expensive as bank interest was very high at 13-15 %. At last desperately wanted a 600 cc i went to kawasaki to check 650n as it would be lessor cost but was flooded with offer like bajaj's 8% interest and its new graphics i booked it without test driving it but when i took the delivery it was a feast of torque which is not even close to benelli. Its a great experience when ever i open the throttle and complementing mileage of 20 kmpl within bangalore traffic is incredible its glossy finish and green color is a good head turner. Its a great value for money as compared to any 600 cc segment or its younger brother ninja 300. I can never miss its comfortable seating which most of the street bike don't have.
Pros every thing like easy handling comfort mileage power. It handles like a small bike when needed matches up to the liter-class bikes.
Con is breaking is bit nimble and its tyres do not match up with the power as by which a rider will lack confidence but the new generation ninja has over come the issue. With its racer looks.
Tips for Kawasaki Ninja 650 
Think nothing its a best value for money sports bike with raw power. If you are looking for sound also then go for z900