Together with the decent phase 90, which was only equipped with a speed controller, the phase 100 is probably THE vintage phaser effect. The classic phasing sounds of the 70s are not a problem, but Eddie Van Halen liked to "spice" his legendary lead sound - especially on the early records - with an MXR phaser
The MXR 100 can be used with a rotary switch to set different waveforms, which allows for more spectacular and modern phasing sounds.