Soft and Warm Vintage Reverb. That's what Keeley was after here. They wanted people to recreate some of those classic sounds in a live setting without a DAW or other expensive packages. Guitar players need a plug-and-play chamber reverb that gives them the classic sounds they are used to and want to emulate.
You can easily set the Decay to determine the length of the reverb. The Pre-Delay is used to match the classic sounds of vintage recordings, going from extremely fast doubling in the reverb to a slapback type of sound.
The Brilliance Control allows you to have the same types of tools to filter and fine tune the reverb, which allows for soft reverbs, deep and sublime reflections, bright and reflective ambience-whatever you chose. You are now the studio engineer to your own sound!