I am a T-booster skeptic. I've read about DAA which is what brings me around to this one.
The first time I tried this product I stacked it with Test freak and I actually started seeing some really nice results. Put a noticeable bit of strength on in a short time frame, which was considerable as I had been training for a few years by that point; we're not talking Kilos on my bench but definitely able to squeeze out a couple extra reps here and there.
This time around I am using it in isolation, a few years down the track again but after some time off training... The only thing I can report is deeper sleep, which is great but not what I was chasing with this product and I am unsure if it is related.
So I suppose, from my own experience, I'd recommend stacking this with Test Booster.