nissan maxima 1996 worth to keep

[cromero1]

my father bought a 96 maxima three years ago, I paid half but didn't see the car until it was ours. Black exterior, interior (leather), no cold AC (I live in Chicago). Plus the car happens to be rebuilt, hard to open doors, steering wheel is off set. The computer is 2 years old, we had to change it. It was about $4500 for the car. I just started getting into cars, should I completely buy it from my father and make it right? or let it rot and get another car? it has been his regular car since last year, lack of care from him has built noticeable rust at the bottom as well.
I know very little or nothing about if should I stick to it, or how much miss use can a car stand to still be worth keeping.

thanks