This digital/analog hybrid machine (digitally controlled analog oscillators and analog filters) is great at producing soft pads, punchy basses, and sharp leads. It comes with 320 factory sounds which are rather OK, but editing via the front panel was a pain so I had to make a Windows editor for it too not go insane!
The MS6 is one of my favorites. It sounds great! You can use separate envelopes for the volume and filter cutoff frequency if you like. Another nice feature is that it's multi-timbral. You can assign the six voices freely to up to six parts, all on different MIDI channels if you like. I don't use this feature much, but it's nice to know it's there in case I need both an analog lead and an analog pad. If you're looking for a deep bass synth, however, this is not the ideal buy - it doesn't go very deep. The MKS-50 is better for this purpose.
Being inspired by the work of Ricard Wolf, I decided to try to enhance the original firmware. After quite a bit of work I have actually managed to release a new version giving the ability to switch banks and control all tone parameters via MIDI - a huge improvement in my opinion! Check out my Cheetah MS6 Resource Center for more info!