Well, this is a nice little gem! A free, cross-platform, dirt-simple compressor that delivers a punchy sound that is great for enlivening instruments. I could see this getting a lot of play on drums, and also on things like pianos, that benefit from a strong attack and added sustain.
The interface is tasteful and appealing; a nice "aged" look that signals what to expect from it. And, of course, the two-dial compression solution - you drive it with the input and compensate with the output, 1176-style. Simple. Done. The VU meter gives you a nice, attractive readout of gain reduction too.
The compression character is nice and snappy, with a strong attack characteristic and long-ish attack, super-ideal for snares and adding ye olde "punch" to material. I'm lucky in that it just naturally gives off a kind of compression I tend to favour, so I think I'll be using it a lot in projects. As a composer-mixer-DIY guy, I tend to favour simple solutions for those times when I can't take an hour to dial in the perfect compression. It's nice when it just has it.
An almost-instant update just added a new feature, a "relaxed" button which allows for a more natural sound. So now you have two free compressors in one!
In a way, it reminds me a little bit of Molot, another wonderful free compressor that can drastically change your input signal. You just don't have to worry about any settings with this one - at all!
To sum up, I highly recommend, and I love that it's cross-platform. A big kudos to Klanghelm for offering this freebie, and considering this is just a "snapshot" of its bigger brother, I look very forward to checking out the full version (and at $20, it could be a real threat!).