We stopped by en route from Vegas to Anaheim. Having driven parts of Route 66 on previous visits to California, and with kids who love the movie Cars, we thought it would be a nice place to break the journey and take in some of the history. As other reviewers have said, the free entry is a bonus and our kids (hopefully) helped out by buying some mementos. Writing is having just subjected myself to the frenetic freeways of outer Los Angeles, it was nice to have been reminded about a time when travelling was as much about the journey, rather than simply reaching the destination in the shortest possible time. The only thing I would add is that it is not too well signposted when heading into town from the east (from Vegas); make a right on First Street and over the railroad bridge. Oh, and it probably doesn't pay to ask for the quickest way back to I-15 as you leave (sorry!).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.