Former 808 owner here, the UI is pretty good, and well done. The sound is, well not an 808. I know this is more of a look what can be done sorta project, and maybe 100% fidelity wasnt your goal, but I would almost prefer the rebirth approach to emulating an 808 by using samples at various settings to match the knob values. In some ways I think you made a decent CR-8000 emulation with the sounds(the cowbell and hat remind me of that)

Anyway, dont want to take away from what was obviously a lot of work. I just want it to sound more like an 808 :)