What happened to EHX? Nirvana fan club? This is usable chorus for different type of sound (blues, hard rock, classic rock, pop, jazz, metal, extreme metal) which I tried. 
 
I've tested it on: 
Gibson Les Paul Faded 2018 
Fender Stratocater Deluxe 
Marshall DSL40CR 
Marshal MG10 
 
Pros: 
Great sound 
Nice design 
Strong box 
Analog sound 
3 command only - easy to handle and experimentation 
 
Cons: 
For God sake, don't put Nirvana everywhere. Yes, you can easily make Nirvana sound, but you can make manyu different sounds, so please stop advertize this effect with Nirvana. I opened package and found "your Nirvana@. I like Nirvana, I listen Nirvana almost every day, but I haven't buy Electro Harmonix Op-Amp Big Muff Pi Fuzz (valve based and great fuzz) only because it fits good for Nirvana only and similar bends. Think about it!