It doesn't do much but what it does do sounds really good. A very believable analog modeler with a voice that's still uniquely its own. And its free.... I went through a period where I was fucking with this a lot while I was arranging songs. Its a low CPU hit so I would have a million instances of this or synth1 as place holders while I was drafting sequences to assign to other instruments later. I haven't been using this one so much lately, dunno why.
Straight from the developer's website: "Charlatan is a polyphonic, subtractive virtual analog (VA) synthesizer plugin with focus on sound quality and easy usability." There it is, pure and simple. You have 2 oscillators, hard sync, ring mod, unison, noise generator, LFO, a filter section with 4p/2p LP and BP, and 2 ADSR envelopes. All of this is in an easy to understand, easy to use, low CPU package. Leads, pads, sweeps, basses, you name it - you can create them all. So go get it.