Watch the Classic Vibe online guitar lesson by Jeff McErlain from Guitar Effects Survival Guide
For years I thought David Gilmour was using a phase shifter until I got my first univibe pedal. The univibe is my favorite modulation effect, sometimes to a fault because I use it too much. Anyway, I love its distinctive warble that I never grow tired of, but like any effect of this sort, be mindful of how much you use it. These things can become a crutch of sorts. Also like any modulation effect, experiment where you like them in your chain.