I got the exact bike you're looking at but it's my 2nd bike.
I'm 5'4 and 130lbs. Back when I started out on my cbr125, I thought the ninja 250 was quite a big bike already and fairly heavy (for me) to get off the kickstand.
When I jumped the gun, scrapping the deal I was going for as 2nd bike (GS500F), the ZX was quite the beast on the throttle.
Over 40,xxxkm later now with my ZX I just got back from my very first trackday.
I've practised lots for this moment, looking like that, riding to the limits of my stock bike. Admitting, I used the streets in the middle of the night as playground. ATGATT !!!
Here's what I tell everyone who wants to start riding bike.
Buy the Ninja 250, since 08 they look very sleek. Get as much gear as you can afford, that's why they sell Kevlar jeans these days... no one would ever notice it's bike gear. Don't cheap out on a $99 Helmet.
Ride the 250 for min 5000mi or 2 full seasons (canadian season=5months). When you sell it (given you didn't drop it once) those bikes resell for 80-90% of your purchase price (given you bought from someone private, not brand new or dealer).
All in all you just gotta pay your insurance and gas, the rest is like learning to ride for FREE. I hear it too often people don't wanna lose money on purchasing 2 bikes within a short period of time.