The book Windows on Main Street by Chris Snyder is well written and fun to read. It could really have been a great book. Unfortunately it is much too short (26 light pages).
The idea is to explain to park visitors what the names on the windows over Main Street stand for. Chris therefore shows some of the windows with a little profile of some of the Imagineers and executives that they feature. This is very nice for a first or second time park visitor, not nearly enough for real Disney enthusiasts or Disney historians.
There is one great aspect of the book that in itself makes it worth owning though: it contain at the end four pages listing all the names of all the individuals featured on the windows (with their locations). This is a great reference and I am really thankful for it.
So this is not a "must have," but if you go through the parks (yes, it's a park exclusive) it might be worth picking it up.