I've been taking it for a few weeks. Definitely one of my favorite supplements I've ever taken for CFS. I feel almost completely normal energy-wise (although post exertional malaise is another story).
Benefits I've noticed: Improved concentration, major improvement in memory, energy, seems to have gotten rid of my chronic gut irritation. I wake up much easier on it. I have to actually watch myself carefully when working out because I'll easily push myself too far and get some PEM the next day or two.
I should add that while it's the only thing I've added to my regimen in the last 4 or 5 months, I do take other mitochrondrial-boosting supplements Acetyl l carnitine, and alpha lipoic acid which no doubt have synergism with PQQ, but PQQ is where it's at.
I take 10mg bid.
Some stuff I found interesting when doing a little research on it:
-Pyrroloquinoline Quinone Stimulates Mitochondrial Biogenesis
-Pyrroloquinoline Quinone (PQQ) Prevents Cognitive Deficit Caused by Oxidative Stress in Rats
-Effects of pyrroloquinoline quinone on glutamate-induced production of reactive oxygen species in neurons.
-Further evidence that pyrroloquinoline quinone interacts with the N-methyl-D-aspartate receptor redox site in rat cortical neurons in vitro.
There's a lot more info on it though. Has anyone else tried it or have any thoughts on it?