I use a single speed exclusively for commuting. Hills and headwinds come with the territory. The key I think for single speed is to gear it correctly. And when I say correctly, I mean for you and your type of riding. You can gear it for hills but suffer on the downhills and flats or you can gear it for the flats and downhills and suffer on the hills. You need to find that happy medium and gear it there. For me it is a 44 x 18 for about 66 gear inches. Your gear inches might be different.

Personally Like the simplicity of it all and it works well for me. I did go out and buy a trailer and the single speed was tough so I built up a 1 x 9 speed that does the trick. Even though I have the choice to take either bike to work, I always pick the single speed. It is not for everyone but works well for me.