We've used a couple of gallons.
It definitely doesn't smell good enough to use in people's homes.
I tried it for the first time last night at one of the few restaurants we do-- a greasy steak house with lots of traffic.
It really does a great job of cutting through the grease. I was so impressed, I had my helper take a before/after pic during the pre-scrub (I'll try to post it later).
We determined there was no need to pre-scrub the whole place, so just HWE'd and post-padded.
Really good results.