I just downloaded.  There is a smaller GUI version in a folder within the download.  It takes up less screen real estate.  So, I started reading the manual.  Not sure if I hear what I should from first use of it.  What I found interesting reading is the relation between the three compressors.  This is what caught my attention:
 
P1, P2 and P3 – a deeper understanding
P1 is the fastest processor, increases clarity and is also used to set the overall input level to all
further processing. On the opposite, P2 is the slowest processor and is typically used for overall
signal leveling and to recover P1 from too much load. P3 is finally utilized to round the
signal off. Such polishing/finishing always occurs within SlickHDR but is handed over to
look-ahead processing the more load P3 actually shows. If too much load is induced, clarity
decreases and also the volume drops slightly as a tradeoff.

Sounds like it's meant to be a bus compressor. That's where you'd typically use 2 or more comps in series, the first to shave peaks, the second for "glue". Might work on a vocal bus, too. I'd try it on a reverb bus as well. Maybe on a mellow bass track. Listen for a thicker, fatter, more even sound with softer transients.
 
Just guessing, for now. Until I get my interface fixed I can only speculate.

I'm definitely intrigued by this...

Will try it out soon....

bitflipper
Sounds like it's meant to be a bus compressor. That's where you'd typically use 2 or more comps in series, the first to shave peaks, the second for "glue". Might work on a vocal bus, too. I'd try it on a reverb bus as well. Maybe on a mellow bass track. Listen for a thicker, fatter, more even sound with softer transients.
 
Just guessing, for now. Until I get my interface fixed I can only speculate.

Yeah, it sort of does sound like compression in series combined with parallel compression.    Interesting stuff.
 

VoS plugins are becoming more and more subtle...