There seems to be a tendency to generate a LOT of gibberish when using the 'randomize' function, but for the specific sound-type buttons, it's fairly spot-on. There are plenty of ways to modify the sounds; easily ten sliders or more and an additional waveform beyond what SFXR has to offer. A nice feature is that a list of the previously-generated sounds is stored, and you can access those at any time.
I've had no problems with exporting sounds; I have not tried the loading/saving of presets or other settings, so I can't speak on those. Up to now, I simply press buttons until something interesting comes out, then I either take it as-is or tweak just a little more to come up with something more to my liking.
For a free 8-bit/retro sound tool, it really can't be beat. I highly recommend it.