We saw the exhibit this past weekend on a trip to Chicago. We had museum tickets for base admission that we "won" at a charity auction at my son's school, so, we had to pay for the exhibit at an undiscounted rate.
The exhibit itself was good. In my opinion, it was on a par with the other exhibits at MSI that visitors pay extra to see, specifically the coal mine and the submarine. It was as nice and informative as the exhibits/shows at Hollywood Studios, and had different artifacts than are seen there. The most interesting factoid was about the house that is Disney's birth place, which is still living.
According to the Chicago tribune, a couple in California recently purchased that house, and are thinking of renovating it and turning it into a museum. That would be interesting.