It's easy to use the Maxon AD-9 Pro Analog Delay as it's only got a few parameters to be aware of. It has three knobs for controlling delay time, delay level, and feedback. Each is capable of changing the tone pretty drastically, but it's not hard to use in general and a manual won't be necessary for most users.
The sound of the Maxon AD-9 Pro Analog Delay is pretty unbelievable. It's certainly up there with the best sounding analog delay pedals that I've used, but isn't the best. It's got a very defined sound that is quite realistic as far as analog delay pedals go. In my experience, it's a better pedal than the Ibanez AD-9, as it just sounds fuller and more authentic overall, although the Ibanez model is also solid for the price. This is a great analog delay pedal for any player's rig.
While not the cheapest pedal out there, the Maxon AD-9 Pro Analog Delay is going to be worth the price if you're looking for a top tier analog delay pedal to use on a consistent basis. I think it just depends on what you're doing with the pedal, but for professionals who are recording and gigging, having a Maxon AD-9 definitely makes a big difference. I don't own one of these as it's still a bit out of my price range, but it's definitely something I'm going to consider once I'm able to afford it...