I do most of my commuting on a fixed gear (a converted road bike with a front brake). I live on top of a decent-sized hill, and it was pretty tough getting up it at first, but you get used to it.

Shifting is great (my other bike is a triple), but life is too short to clean chains and derailleurs. So I save the geared bike for nice weather and ride the fixed-gear when it's nasty out.