I love it! I control the System-100 with a Kenton Pro-2 which makes it really easy to use. All knobs feels great. It's a very good synth for making monofonic techno-sounds
Comments About the Sounds:
Sounds great for being that old. Great VCF cutoff/resonance
(Thanks to Bjšrn Fogelberg for this info.)
and Simon Brunndahl for the pic