1-AD is a great supplement with once exception, it significantly reduces your sex drive...A LOT! If you have a horny girlfriend you might wanna watch out.
However, 4-AD which is also an effective supplement, can correct this problem. That's why many bodybuilders stack 1-AD with 4-AD.
As others have mentioned, your testosterone levels will most likely be way down after your cycle. Therefore it is smart to supplement something like 6-OXO immediately after you are off to maximize gains and minimize ***** tits and other estrogen related effects. While both prohormones claim that they don't lead to these things, most people report that they have undergone these side effects, although significantly milder than actual roids.
At the same time, most roid users who experimented with prohormones claim that the crash after using them was significantly WORSE than actual roids. Another reason why it is important to supplement like 6-OXO after you take them.
From what I gather, the supplements are extremely effective and several people I know reported that they gained 15-20 lbs of muscle on their cycles. Results are generally strongest for ectomorphic body types.
I hope that I shed some light on the subject, and that I didn't repeat anything anyone else said.