I mostly play metal and was looking hard for a good distortion pedal to use in front of my tube amp. I narrowed my options down to this one, an Angry Charlie and The Pinnacle, and basically chose this one because of its built-in noise gate. To my ear all 3 pedals sound 100%, so I couldn't make the decision based on sound quality alone. I'm happy with my choice!
I'm using the pedal in front of my HB Tube15 with the amp gain set to 0. The sound of the pedal is massive, rich and organic. Really satisfying warm, and cutting distortion sound, hard to believe that it all comes from a stompbox - it sounds like a real tube amp distortion channel. The built-in gate works great. The boost function of the pedal does make a difference to the sound and sustain, but I still prefer a separate boost pedal in front of the MXR 5150.
...Which leads us to the only con this pedal has: you have to use a boost in front of it to tighten up the sound for chugging. I use a Maxon OD808. Again, the MXR handles the boost pedal like a real amp would. Highly recommended!