I have tried it as a preamp into the return of an amp and into cab emulator hardware. It works great as a preamp in both cases, with both channels being great and, besides, the clean channel can be a good pedal platform. As a preamp in pedal-format it is a good option, though it lacks balanced XLR outs, cab emulation and power-amp emulation, things other builders (TK, Fr.) have implemented lately in their new preamp pedals. Still, if you alredy have an amp, a power amp & cab, an IR loader and/or an active FRFR cab, you may not need these extras.
I have also tried it as an overdrive (you should use the attenuation switcher: a few dbs less and a mellower sound). Perhaps as an overdrive it may be a tad less convincing, but it depends a lot on your rig and where you place it. Actually, the clean channel can give some extra body and grit to the clean channel of your amp, as if you were stacking low-gain overdrives, and the lead channel may provide a lot of gain, which I think takes a bit longer to set up, but it is a tube preamp so the potential benefits are there: two preamp gain stages may work great or be overkill, so less gain in one or both works better.
The sound is very good and it's a tank! Not too large, though some other tube preamp drives are smaller. A bit expensive, but In Europe we are paying import taxes, after all. You should try it.