The make up of the Fender Blender is generally pretty simple to follow. The pedal has two switches - one to engage the effect/bypass, and one for tone boost. It's also got parameters for volume, sustain, tone, and blend. Those are all the parameters available on the Fender Blender, which is really more than enough to get a wide array of tones here. A manual isn't necessary in my opinion, but I haven't seen it so I can't speak to it's make up.
The sounds that are possible with the Fender Blender are pretty awesome, as it's a great mixture of fuzz and octave sounds, which really go hand and hand here in this setting. It's also got a tone boost which makes the pedal all that much more versatile. The fuzz is really thick sounding, and I actually like it best for lead sounds as you can get a ton of sustain with it. I've used the pedal with other Fender products, a '76 Fender Twin Reverb and a Fender Jazzmaster.
I'm really a big fan of the Fender Blender overall as I think it brings a lot to the table in a variety of different ways. I like it best as a general fuzz pedal for lead guitar tones, but it also works well for rhythm tones as well as for getting an extra thick fuzz/octave sound. The price is a bit much, but this is a very high quality pedal still worth check out regardless of the price, but there are definitely pedals out there that are as good for cheaper...