This is a great pedal for when you really like the sound of your amp when overdriven but you want a little more gain. I have found that this pedal can be really bright so setting the tone to around 30% really helps this pedal to sound the best to my ears. The gain can get a little wooly when past 50% so I usually keep it below that.
At around $100 this is a great pedal to have in addition to a tubescreamer as this pedal is not mid forward like a TS9 or similar. I have found that it sounds good with amps that are Marshall or Fender style.