A few years back I converted my 35 year old 10-speed to fixed and really fell in love with fixed gear riding. It's different than geared or free-wheeling because of your heightened awareness of your direct connection to the bicycle and to the road. The simplicity and elegance of a fixed gear (and SS too) is also very refreshing.
Modern geared bikes are wonderful machines but for pure riding enjoyment the fixed is hard to beat.