For Windows, no separate installation of Python was required. That makes it rather similar to the MoinMoin Desktop Edition for Windows in this respect.
Unlike MoinMoin and Instiki, WikidPad does not have a webserver built into it. Thus, WikidPad is a single-user experience. You can export pages to static HTML files, however (all pages → one monolithic HTML file, all pages → one HTML file per page, one page → one HTML file).
As a stand-alone application it offers some goodies such as a lot of keybindings, an automatic tree of pages that acts like folders in a sidebar on the left, icons for pages to be used in that sidebar, etc.
This tree is interesting. All pages that link backlink are considered to be "children" of the current page. Assume you have a page called A linking to pages B and C. What you will see, then, is this tree:
+-A | +-B | +-A | +-C +-A
So, multiple parents are no problem: Each page is listed on the top level, and below each of its link targets (the "parents").