I have the "ratty" 1970 paneling mostly off my living room walls, and the old plaster seems to be in OK shape minus the nail holes.
The "wood like"/osb/whatever paneling in the bedrooms are maybe a tiny bit thicker, around 1/8 inch, and in more paintable condition. I'd prefer the look of the old plaster walls painted and they seem to be in solid shape underneath. Winters where I live can get subzero cold, and summers get very hot though. Are there any significant insulating benefits to leaving paneling and painting it?