The make up of the Lexicon Prime Time takes a minute to get used to as there is a good amount going on. However, once you break everything down it isn't really all that hard. It has main sections of sliders for input and output mix, as well as parameters for delay amount, cutoff, a VCO, and a variety of other parameters. It also has an LED screen to show the amount of delay in millisecond. I wouldn't think that the manual isn't all that readily available since this is an older piece of gear.
The array of different sounds possible with the Lexicon Prime Time make it a very powerful piece of gear. Like I said earlier, you can definitely get many sounds beyond what you would think of as a traditional delay. I've used the Prime Time for many different applications - really just whenever I think I might want to try some interesting delay sounds. You can really use it on just about anything at all, as I wouldn't say there is any one application that it works best with. It's overall an awesome sounding delay and effects box that allows for plenty of tweaking.
Having used both the Lexicon Prime Time and the Prime Time II, I'll have to say that I like this one better. Lexicon is known for making some of the best digital reverbs and delays out there, and this one is definitely one of the more unique effects that it has. I don't know how hard or easy it would be to buy or find one of these, but I'm just glad I'll have access to it for as long as I'm working where I am...