Fixed gear bikes work great as an everyday commuter. It what I use.
A fixed gear bike is fun, as you have already found out.
The fixed gear drive train requires less maintenance and won't require adjustment.
Its also cheaper.
I always use rim brakes but in case the brakes are non functional you still have a backup in back pedaling. I have had this problem with snow and ice and in one case due to mechanical failure.
You vary your speed by your cadence not by gearing. Your top pedaling speed will be reduced but with a 72 gear inch (42x16) setup you can still exceed 25MPH. Flat ground speed is often not a problem, however going down hill your feet have to keep up with the bike. This limits you top speed going down hill.
For short climbs or moderate grade climbs, I climb as well or better on my fixed gear. It is easier to stand and crank up the hill. However for long climbs or steep hills the low cadence can be a problem, but there is always walking.
I find a fixed gear very practical for everyday urban commuting. My ride is 8.5 miles each way and involves city streets and a decent into the river valley and part way up the other side. Ofcourse the return course involves climbing back out of the valley. I have ridden my fixed gear on hilly 35 mile rides and I know others than have done mountainous 100 milers.
Craig