One of the more popular aspects to drop D tuning is that you can play 5th chords quicker. Rather than sliding two fingers up and down the neck of the guitar as you do with normal 5th chords, when you use drop D 5th chords you only use one finger. And if the sequence of chords are close to each other then you'll find you can move quickly between them. This example show how much easier it is to play a fast sequence of chords using drop D 5th chords. Try playing the song below and use normal 5th chords and see how long you can keep up for.

This next part is in 5/4 timing (5 beats per bar), if you're not sure about your time signatures learn about it in the reading sheet music section !