At a quick glance I didn't see mention of what voltage it's running the 12AX7 on, but most of these type pedals (tube driver included) are running the tube in what is known as "starved plate" mode, or in other words, very low voltage. Doesn't have the same characteristics as the same tube run on the normal (high) voltage, but they do work & have a unique sound. Over the years I have made several of these type pedals for people, though I use a small transformer to power them off the mains power, putting a little over 20VDC into the circuit.
Some of these pedals (like the tube driver) run the signal through an IC before it hits the tube. Whether or not this does is anyone's guess. The ones I've made don't.
I wouldn't really expect to be disappointed, they usually do what they're called,,,, overdrive. Hope it works well for you. Cheers
Edit:
I actually worded some of that wrong,,, these are usually AC powered by a means of a wall wart/plug pack that plugs into them, whereas I put a small transformer inside the pedal enclosure. Cheers