G for getting off opiates? Eh... It helps. By no means a replacement therapy. I'd put it slightly above other comfort medz and way below more opiates.
The taste has always made its usefulness somewhat self limiting. Have you ever started puking while brushing your teeth during wd? Well, I can about start dry heaving just thinking about the taste of G during detox. You can try to mask the taste by putting it in some juice or something. After redosing many times, even juice doesn't mask the taste, and it makes me gag immediately.
G has, however, meant the difference between one semi-miserable hour of sleep and no sleep at all. Of course, you will wake up almost exactly an hour and fifteen minutes later in a pool of sweat. Still, better than no sleep, and with a couple more doses through the night, one can manage to get a few hours of sleep during some pretty miserable withdrawals.
It's helpful to have around, and makes things *a bit* easier. It is no replacement, though. It does help considerably once you are through the worst (first 3-5 days). Nice to have something you can take a few times through the day and catch a little buzz. It is helpful, just not that helpful. Not even close to a magic bullet. I think it's best feature is being able to knock yourself out and get a bit of sleep, even if it isn't more than a couple hours a night. Far better than no sleep.