The pictures are much better on the Scholastic website linked to above, but I'm posting a couple of the ones I took in order to point out a few things (and to see if I can figure out how to successfully post pictures to this blog.)
Here's the thing that impressed me the most: they had the driver's seat on the LEFT (because it's a British bus, of course.) Also, the seat is an armchair with the big wheel described in Harry Potter and the Prisoner of Azkaban. This seat is pretty obviously for show... it looks like a real seat on the right hand side folds down for the actual driver.
The bus is actually a double-decker bus (although it is painted on the outside to look like a triple decker) and the windows are also painted on. The actual bus is filled more with computer equipment than with wizard furnishings. Each person on the bus (and who has filled out an extensive release form) has a chance to record a 20 second video about why they love Harry Potter.
I was one of the only adults on the bus... and I peppered the Scholastic crew with questions. They said they get a lot of strange looks driving from city to city and a lot of near accidents as people on the interstate come to virtual standstills (while driving!) to pull out their cameras. Only one person (the driver) actually rides in the bus... the rest of the staff are in a different vehicle.
Just imagine the looks they get at truck stops and toll booths.