It took me
yeears to figure out how to use it in a musical setting, but once I was able to finally grasp what can be done with it, as well as the unique relationship it can have following that particular Maxon phaser, I can easily say it's one of the coolest sounding pedals I've ever played.
It can do outlandish synthesizer stuff- the band I'm in BUSTARD used to build a wall of sound at the end of an old song where I'd get the Maxon feeding-back (feed-backing?) a solid droning signal into the ring modulator and out of the DL4 delay, then I'd get down and play my pedal board like an instrument. We called it the "knob solo" and it was super fun to do and hear.. alas, we're a 3-piece now instead of a 5-piece which makes most of my duties much more utilitarian.
Another super cool thing about these big Moogers is that each knob can be controlled via expression pedal- you can see that little one I built in the standing enclosure with the blue wheel below.

I used the wheel plugged into the MIX expression jack so that I could swell the effect in, rather than introducing it over a sharp threshold using the footswitch.
Contrasting the wild synth noises it can make, it also can do a very beautiful sounding tremolo that can be set to rhythmically speed up and slow down. This effect is subtle and difficult to dial in so I never used it live but it would be really great for recording ambient stuff in a very pretty way.
These effects are NOT just for guitar- I feel like you could plug almost anything in there and instantly be "cookin'."
The build quality is astonishing, seeing as it still works 100% after a rather unfair battle against a 1991 Crown Victoria station wagon.
CONS: it takes weird power, it takes up space, and the learning curve is a heckuvathing.. oh, and they go for crazy money these days- if you can afford one and it suits your vibe, then all the other cons are totally worth it!