Like others have said, this is an incredibly versatile distortion pedal and one that is unbeatable at this price point. It's a very musical sounding distortion that can go from open, sparkly low-gain drive to a think fuzztortion that would transform your clean channel into a whole new beast. Have one channel for raw, ringing overdrive, the other for a huge wall of sound, or set them both at the same type of drive (boost/normal) but with different level of volume or distortion to give you that push where needed. It really has many uses.
I say this as I mostly play it in the clean channel of a tube amp, and that's where it shines and sounds most organic. Playing it in a solid state amp clean channel sounds great as well, only don't try to push a distorted channel with it. It doesn't do well pushing other pedals but it takes overdrives in front of it like a champ. I've put in a Tubescreamer 808 before and it gets me to ultra gain when both are engaged, which is amazing for thick solos or heavy Drop D - Work.
And the best of all: top mounted-jacks ! T-Rex were way ahead of their time :) The only complain I have is the tone knobs are flimsy and seem like they could break if you're not careful, otherwise A+++!