Vimwiki, amongst other things (and I'm still learning) supports not just its own wiki syntax, but also markdown and mediawiki (there's an option to be set and it has to be after v2.0); it has a decent diary system with automatic index page generation; it can automatically convert the entire wiki+diary into html if you want that; and it has a few other nifty things like checkboxes for to-do lists and the like. Worth taking a read through the features part of the project website at least.

Off the top of my head, some light formatting support, and simplified "link" navigation.

Taking your example - Yes, I know of "gf" and "ctrl-o". VimWiki changes that to "enter" and "backspace", and requires no extra steps to visit filenames with spaces.

Not wildly ground-breaking, of course, but I like the end result.