I've never had any troubles using the Klon Centaur as it is a very easy pedal to use. It simply has three knobs that control gain, treble, and output. It really doesn't get much easier than this and even those with little or no experience with distortion pedals shouldn't have much trouble using it. I've never seen the manual for the Klon Centaur so I can't speak to how helpful it is, but it really isn't a necessity as the pedal is easy enough to use on its own.
The sounds that are possible with the Klon Centaur distortion pedal are overall pretty incredible. In a lot of ways I feel that this pedal is somewhat underrated simply because it isn't all that well known, but for those of us have used it know that it is really just as good as any distortion pedal out there. While this isn't an extremely versatile pedal, it has its own unique sound that is hard to replicate with any other pedal, and for this reason it is great to have this pedal around whenever I want to get this type of sound. I've only used the pedal for recording and usually use it with a Fender Strat and a '76 Fender Twin Reverb, so I definitely get a pretty accurate representation of what this pedal sounds like. If you haven't heard this pedal yet, it is a must try for any fan of distortion pedals.
I've been using the Klon Centaur for about three years and I can't really say that I have any complaints about it. It has a suburb tone quality and is extremely easy to use and operate. If you are looking for a unique distortion pedal, I would highly recommend trying one of these out to see if it will fit your style. Even though it isn't the only distortion pedal that I use, when used in tandem with others it adds a new color that isn't possible without. The price isn't all that cheap, but at the same time isn't incredibly expensive and serious players should be able to afford it if it is something that they want. Overall, the Klon Centaur is a great distortion pedal that is a must try for any guitar player.