I have been working out with a personal trainer for a few months now and we finally started incorporating Jack3D into my workouts.
I started out with a protein shake + creatine 90 minutes before workout and protein shake within 90 minutes post workout.... but now instead of the pre-workout creatine, I use a scoop of Jack3D in a separate drink.
This flavor turned out to be yummy...I can dump it in a glass of water and down it easily.
I've taken it 3 times so far, at the 1-scoop level, and it does add a pump to my workouts. I think as I use it more, it will get even better.
I was nervous that it would make me jittery or anxious but I have not experienced those side-effects...no tingling or strange sensations. Perhaps as I use it more or take larger dosages (READ THE LABEL!), I'll feel it more... but I like this current level because it gives me an extra pump for the workout but when I'm done, I can sit still in my chair and get work done ;)
So anyway, if you're nervous and just starting out, it's worked out good for me so far. I may have taken less than a full scoop the first time, just to be safe, but I felt good/fine each time. Oh, I bike 15 minutes to my gym to work-out and I haven't felt like a spaz on the road or anything so that's good too ;)