Pretty much like my experience when I got my iBook. Nice interface, the iApps work well, set up was a snap, some commercial software was needed (Office, EndNote) and a nice UNIX system under the skin for downloading, testing and running open-source software and systems (Makes testing things like blogging software really easy). Again like the article writer I use Linux for servers (Greenflame’s on a Linux box) and OSX for the desktop and development.
See: The Mac Mini Experience – OSNews.com
Not sure I’d buy a Mini but some of the project that people are using them for (integration with home theater and cable TV) look interesting.