It's a great tube compressor. Same flavour as the Waves CLA-3A but this is free. I've compared the two side by side and I haven't noticed a difference. The possibility to adjust attack and release time is a plus. Highly suggested on vocals and drums. I can't believe it's free.
To anyone using it on a master bus, be aware of the high frequency roll-off. It starts at around 8 kHz and takes away around 1,5-2 dB. I tested it with SC HPF and DRIVE both at 0%, with only 1 dB of gain reduction, 100% WET.