My son and I loved it, but I am not sure how any less appreciative spouse or kids not interested in cars would fare. It is not terribly expensive, however, so if you are in the area I would definitely recommend at least an hour for this attraction.
There is a wide range of autos, my son played 'find the oldest car' game which kept him quite entertained. I gave him my digital camera as he got bored (I was still going strong reading about each car) and he clicked away to his delight.
The range is from Ford's original quadricycle, through plenty of cars from 1900's-1910's up through muscle cars of the 1960's and 70's. They also have some dedicated race cars and a few custom cars. If you have some extra cash lying around they even have some cars for sale!
It's not far from Old Sacramento which is a revived Western-style town with wooden sidewalks; if you squint you can imagine dusty streets with saloons, horses and maybe a gunfight down the street.