If you've ever used a compressor before, you will be able to use the FMR Audio PBC-6A without a problem. It has pretty much all of the basic parameters associated with compressors. You've got knobs for drive, knee, attack, release, and output, as well as switches for 'thick' and bypass. It also has LED metering for gain reduction. Not too much else that you need to know about this unit, so unless you don't understand what these parameters do, a manual is not needed.
While a bit different than it's counterpart, the RNC (Really Nice Compressor), the FMR Audio PBC-6A has an overall very impressive tone. It is versatile as I've found it useful in just about every situation I've used it in. However, I do feel that you need to know this compressor in order to use it in the right spots, as it isn't for use with everything. It will hit your signal very hard! Of course you can back off a little bit depending on how you set the parameters, but in general this is a heavy compressor for sure...
When compared with the Really Nice Compressor, the FMR Audio PBC-6A isn't the same type of bang for your buck deal, but is nonetheless a very good deal. They set the bar very high with the RNC, which is probably the best deal on a compressor out there. Having said this, the PBC-6A comes quite close, as you're getting a top of the line compressor for around $500 USD. Absolutely worth looking into for both home and professional studio owners alike.