To set this straight, this is not a pedal that works no matter what,and very few people use it in modern music. Big Muff is a fuzz (not a distorsion pedal). But most importantly, the Bifg Muff will not help you unless: you use a tube amplifier AND an overdrive; using only the Big Muff, even on a good amp, will get you a heavy fuzzy sound (closer to Heavy Metal than to the desired Gilmour).
HOWEVER this really is an amazing pedal: i am using the Big Muff for almost every solo, i used it in the studio, live gigs, i use it at home. I am always getting perfect sound, excellent sustain and great disruption for the solos (sometimes i use it for heavier rhythm lycks as well). I use it however in the following way: Fender Deluxe Reverb amp (also used other tube amps with it, Marshall, Bronx, or Fender Twin) - key is to use TUBE AMP, then i am always using it through my Ibanez TS9 overdrive (the Big Muff CANNOT BE USED without OVERDRIVE). This is the way i am getting the smooth sound that gets close to Gilmour or Hendrix.
Controls: volume (easy - you need it at >50%, guitar through Big Muff needs volume in order not to lose distinctiveness, especially on stage), tone - depends on preference, veeeery effective little twist, then sustain - less sensitive, anything in the range 40-80% will do. This pedal is NOT EASY TO SET, try all alternatives, experiment. This is why my score for Features is not top, as you really need to try different setups before concluding on your sound.
Two more things worth mentioning: the pedal is noisy, you will appreciate a noise filter (i am using a Boss noise gate), secondly it is usefull for solos to add a delay to the Muff+overdrive set (i am using an average analogue one, i also have my amp's Reverb setting at 3).
Again, i have to say that each type of Big Muff interacts very differently with each amp and overdrive pedal (and i really mean veeeeery different!), but if you find the right combination, miracles happen. My Deluxe Reverb amp and TS9 make wonders with the Muff. The Muff has defined my distorted sound, and mostly guided my work with solos, i would not change it for anything.