The Mac Mini has always been an amazing piece of engineering; reasonably powerful innards paired with an attractive look, compact footprint and reasonable price. The 2011 devices are no different; I ordered one to run the media network in my home (notably, as a Printopia, Air Video and NFS server). I have a reasonable amount of storage, and the old notebook I was using to power all of it was failing (it is over 5 years old).
This new device has just slotted in and gets on with the job. Very powerful, and probably wasted in pure "server" mode, but a great asset to any home (media) network. Highly recommended!
PS. Upgrading the RAM in this one is very easy. You unscrew the lid, and pop more in. Easy.