I understand that people like it and that parents like taking their kids on it, but its been around since the park opened, and they haven't really done anything exciting with it since. The cars are still loud, and stinky, the peddles are a little tough to keep pressed down for the whole trip. The center guide rail is a pain when you bang against it.
The main compliments that people seem to give is either they want their kids to experience the same fun that they experienced when they were young, or Its a classic Disney attraction that's been around since the park opened, or Kids still love it! Honestly though, I think the main reason people like it is nostalgia. It was something they liked when they were young and they want their kids to experience it too...but it takes up a LOT of land that can built upon.
I personally have no love for the Autopia, it hasn't been "Walt's" Autopia for over a decade so I'm not really sure where the nostalgia stems from, but I personally cant wait to see what they do with the space
BTW, Screamscape reported this today:
Tomorrowland Update - Rumor - (6/29/12) An anonymous tip sent in to Screamscape confirms that the word going around Disneyland is that Innoventions and Autopia are very likely to be walled off by this time next summer as they work to remove them, along with the old Peoplemover track around this area as well.