The make up of the DOD FX56 American Metal is extremely easy to follow as it only has a few parameters to work with. The pedal has knobs for level, presence (which is like tone), and distortion. Even if you don't have much experience with distortion pedals, this is as simple as it gets and I don't think that users will have much trouble figuring out how to use it. Because of this simple configuration, I don't think a manual is necessary although I haven't seen it so I can't say too much about it.
The sound quality of the DOD FX56 American Metal is pretty average. It isn't anything to write home about, but it does have a decent tone that is suitable in certain situations. While I can't say that I would use the pedal for recording, this would get the job done for practicing or even for live shows depending on the sound that you are going for. I usually use the pedal with a Gibson SG and a '76 Fender Twin Reverb, so I'm getting an accurate portrayal of what the pedal sounds like. While this isn't by far my favorite distortion pedal, it does have a decent sound that will get the job done more times than not.
I've been using the DOD FX65 American Metal for about ten years, as it was one of the first distortion pedals that I used when I first started playing guitar. While I wouldn't recommend the DOD FX56 American Metal to professionals, for those looking for a cheap option for some distortion, this will get the job done. DOD doesn't make the most well made pedals, but the FX65 should last as mine has as long as you treat it properly. All in all, the DOD FX65 is a serviceable distortion pedal that is good for those looking for a cheap distortion pedal.