The Lex has a very natural sound - a warm, rich and, to our ears, a very detailed emulation of the real thing with a nice sense of dimensional depth.
There's no tone control, but Strymon seems to have voiced the Lex just right so that bringing up the horn level puts the top end just where you need it. Valve Leslies when pushed hard were valued for their overdrive and the preamp drive here brings that element to the sound, getting subtly grittier as the knob is advanced, but never swamping the sound even at max.
Speed changes are handled well with a natural acceleration/deceleration, and the mic distance knob realistically models real world mic positioning - further out the sound is smoother, closer in you are more aware of the rotation cycles and hear a choppier sound.
Overall the available parameter adjustments allow you to realistically reproduce plenty of the variables of a Leslie cabinet's operation. In fact, it's rather difficult to actually dial in a bad sound.
There's no doubt that playing guitar through a rotary speaker will give you a multi-faceted sound with lots of subtle nuance that's a challenge to recreate using electronic rather than electro-mechanical means.
But recreate it we must if we don't want to be lugging huge cabinets around (not to mention mic'ing them up and servicing them regularly) and this pedal does the job extremely well.
To our ears, the Lex offers a highly natural representation of the Leslie speaker sound, with a set of parameters that can shape the sound exactly to taste without straying beyond the boundaries of what the original is capable of. It's ideal if you want to get as close to the real thing as possible.