I have done this tour in February and thought it was excellent. You get to see a lot of things that you would not otherwise see on other individual tours such as the central maintenance and repair facility, xmas storage warehouse, laundry facility, floral department and much more. It is seven hours including a long lunch at mama melrose, and there is considerable walking, however, the tour does use a dedicated bus to go from park to park, and even sometimes backstage with in a park. The walking was not tiring because you get to rest on the bus between stops. My only complaint about the tour is we spent very little time at MGM(we went there pretty much just for lunch) and did not go to AK at all. Even though I have taken individual tours in AK I would have like to see some more backstage areas not covered in them. Also, MGM no longer has an individual tour. Having said all that, I still highly recommend this tour, Like I said, you get to see mostly stuff not covered on any other tour.
Hope this helps
Lancer