First and foremost, MediaWiki does not support the concept implicitly linking all CamelCase words that are introduced into the text. In contrast, all linking is explicit which is a very welcome thing as it prevents overlinked texts that provide no contextual meaning to the reader. You might argue that a text might be underlinked then, but as it is a Wiki still, it attracts changes as long as the content is considered „not complete“ by the readers. So missing links will go away as missing information (and typos) do.
Another interesting concept is the introduction of namespaces that makes „relative“ pages possible and allows for some interesting solutions for „internal“ pages, automatically generated pages and so on without poisoning the default namespace. Pictures are managed in their own namespace and each picture is treated like a separate page but can be included by reference in other pages. This makes maintenance easy and concise.
The upcoming version 1.3 of MediaWiki is about to introduce RSS feeds and XHTML/CSS based skins so more good news is ahead. I would be happy though if somebody would port the system to PostgresQL but I don‘t see this happen anytime soon.
Installation of MediaWiki is a bit confusing however. Once you know your way with MySQL you can concentrate on setting up the Wiki itself. The INSTALL document talks about an „experimental web-based“ installation which in fact is the only viable solution. It doesn‘t offer all the options, but you can dive into the LocalSettings file and tweak it to your needs. Just don‘t try the „classic“ way described in the INSTALL files: the developers admit that it is just broken and destroys you initial setup right away. Strange.