The Planetarium is a stereo reverb and chorus, running into an echo (with stereo modulation), which then runs into a compressor (with external sidechain).
It will create smaller more realistic reverbs, but it wasn't really designed for realism. Where it really excels is creating huge lush swirling reverbs and echoes, most at home in ambient and electronic genres (and maybe some 80's synth pop). Combine it with a fuzz pedal though and you've got instant post rock - It will create the most monstrous walls of evolving sound....then kick in the side chain compressor and make it pump - live to a drummer (or anything else) without needing a computer or click track.
The chorus and modulated echoes make a beautiful combination and will create tapey wobbly magic from any instrument you choose to run through the pedal.
If you want to make epic cinematic music or blur the lines between electronic/post rock/ambient genres then this pedal will help get you there (but if you are looking for a tool for your Status Quo covers band you're probably on the wrong website..).
View the manual and an in depth video of functions below.