Steel doesn't beat you up on long rides the way stiffer aluminum and CF frames do. Anytime I'm on my bike more that 3 hours or so, I prefer a steel frame, for comfort.
Performance-wise, I will concede that steel is not quite as fast. If I accelerate from a dead stop on my CF bike, I can get up to speed several seconds faster, and with fewer pedal strokes than on any of my steel bikes. This is not insignificant in a competitive situation, but I don't race, and if given a choice still prefer the comfort of steel on many (but not all) of my rides.