This is perhaps the strangest of Yamaha's portatone series, and definitely the rarest. I also own its little sister, the VSS-30, which surprisingly has a few features the VSS-200 doesn't, including a mini sequencer, vibrato, and ability to affect the instrument sounds without sampling them first.
However, true to their quirky nature, this latter feature is precisely what makes the VSS-200 so unique. You can capture any of the 100 (awful) onboard tones into the unit's sampler, and then run the resulting tone through the 9 DSP effects: loop, u-turn, reverse, FM, AM, fuzz, echo, level and pitch; many in combination. You may then layer as many additional sounds into the built-in microphone for some real fun grime cheez. Plus, there's a real ADSR that's fully adjustable.
Happily, there's no automatic power off like there is on the lesser models, so you need not worry about losing your sample after 7 minutes of non-use. Lots more fun than an SK-5, with many more options. Dunno if it can be easily circuit-bent though...
Case is handsome, functional, and easy to navigate. Overall, a lo-fi wet-dream come true. Worth looking out for. A nice addition to your dairy section.