Opinions on Korg Concert c-15s digital piano.

[amc252]

Hi everybody,
Total beginner here, learning to play some jazz as a hobby.
I just bought a used Korg Concert c-15s digital piano with 88 weighted keys and would like to hear some opinions from people who played one.
So far, it seems good, I mean still way above my skills level, very solid (the sucker weights 100 pounds) and well built.
My only doubt is that a couple of keys in the middle range have a sort of slightly metallic resonance.
Also, I couldn't find a serial number anywhere, but I assume it's at least 10 years old.

Thanks in advance for your feedback