i don't ride with brakes on my fixed gear currently, but that's because my current handlebars have not been conducive to adding a front brake since i retaped them for aesthetic purposes.
the disadvantage of not having front brakes is that if you're a cautious-type (which i tend to be around cars) you don't really ride as fast as you could with the mental reassurance of a brake. skid stopping is fun, but it's more fun than practical. having a front brake dramatically decreases your stopping distance, and relying only on your leg power to make sudden stops all the time makes your knees sore.
the disadvantage of not having front brakes is that if you're a cautious-type (which i tend to be around cars) you don't really ride as fast as you could with the mental reassurance of a brake. skid stopping is fun, but it's more fun than practical. having a front brake dramatically decreases your stopping distance, and relying only on your leg power to make sudden stops all the time makes your knees sore.