Haven’t played with it that much, but it isn’t difficult to use or sound bad at all, have gotten pretty cool results even though it feels a lill random changing the sliders, having no idea what the changes will do to the overall sound. Can take a while generating sounds if you use longer durations and note ranges / step sizes spanning a few octaves, which can be off-putting if you wish to a-b compare the synth on different settings. The test-tone will come in handy in this kind of scenario for sure.
Maybe you can add tool-tips explaining how the different parameters affect the outcome, also for things like the drop-down options in ‘Placement’ (harmonic, multiplied, Powered, Waved)?
I think this tool really starts to shine when you adjust the envelopes in the ‘Instrument Settings’, for example adding a slow attack portion in a volume envelope, use some panning and filtering. Maybe you can take a look at Mxb’s Resynth and use his envelope and arpeggiator tricks for your tool as well?
Maybe you can ask vV how he worked around the ‘Script not responding’ notice, using a progress bar in one of his scripts?