I had a li'l Ninja. It served me very well for a first "real bike" (after a Chinese 50cc scooter). 9 months and over 12,000 miles. It's a solid machine. I've been lapped by one at the track.
That said, it's not the bike for me. The suspension is a real weakness, and the low- and mid-range power is seriously lacking. It is flickable. It is fun in the twisties. It would be a riot on the track. It is rough riding, though. I've cruised down the same streets on my KLX that I used to despise on the Ninja, not recognizing them for how "incredibly smooth" they are. I get to the end of the road and realize it's the very same road I got my teeth rattled loose on with the Ninja -- and no road repairs had taken place.
Ninja plastics are as pricey as their Big Brothers' counterparts, but the bike itself doesn't have the same value. Ergo, it's easy to "total."
The gas mileage is great.
It is very hard starting in winter. Or if it's cloudy. Or if it's a day that ends in "y." (The US version is still carbureted. I don't think this would be an issue if the bike was FI, like I believe yours is.)
It's a solid commuter bike. Aside from plastics, parts are relatively cheap. Insurance is dirt cheap. It would be fun on the track. Sticker price is cheap. I only ever had to trailer it from breaking down ONCE. That's way, way better than the KLX, which I've trailered so much that I can't even count all the times (corroded wiring harness, cracked sleeve, cracked fuel line, flat tire, jammed throttle, etc.). Then again, I ride the piss out of my supermoto, and I only ever really puttered on the Ninja.
I would love to try one again for real, knowing what I now know about body positioning on a "sportbike" and throttle control and whatnot. It would be a fun little screamer on the track. I've seen experienced riders enjoy thrashing them and having nothing but a big grin on their face at the end.
It would be wrong to call it a "beginner bike." It is a bike that happens to be good for newer riders, but it's also just decent as a small displacement motorcycle, fit and enjoyable for anyone with experience, too. Its lightweight means much less fatigue. Its "lack of power" means a much more relaxed and less mentally fatiguing ride.
Sportbikes are not my cup of tea. Your first bike teaches you what sort of rider you're going to want to be. The Ninja taught me that I'm not a sportbike girl at heart. I'm a hooligan.