It has been fantastic for me, my log is in my signature if your interested, this has been my second run. I used it when I was taining my son and his results were quite impressive. I will be frank here there does seem to be different levels of response, but most do get very good results.
The results are: Increased strength (as much as 40-80 lbs on some compound lifts), size increase (depending on diet you really need to eat a lot on prime for bulking). Recomp, which I think is the best way to use this product. Not a recomp where you lose weight but eating over maintenance calories and losing fat while gaining muscle. Some of the other benefits are 24 hour pump feeling/ extreme muscle hardness and a real alpha male feeling as well.
The risks are just this, it's easy to overtrain when on Prime. It gets you so motivated and gives you so much more intensity that people are prone to burn out if they're not carefull. The only other risk is your level of response and that you'll know only by trying it. I would try 2 bottles to see how it works for you. The risk is definitely worth the benenfits.