In conjunction with anabolic steroids I can now attest that it definitely improves fat loss and muscle mass gain tremendously.
Without AAS I would say it has some minor beneficial effects that make it worth running, but there's really no limit to how much you can abuse it.
The excess sodium of overusing GHB is very negative and can really mess with your blood pressure and heart rate. Other nutrients can become very off balanced and this will hinder your gains if you fail to realize this. There have been fatalities from GHB withdrawals and the withdrawals build up much quicker than alcohol's do.
It was made illegal because it is a highly addictive, euphoric, gaba-agonist with a very short half life (30-50 minutes) making it possibly one of the most compulsively addictive drugs available. GHB is to Alcohol as Cocaine is to Meth. If it were more popular and its positive effects were well known, I could see it become a problem drug at the level of heroin.
The "date rape" thing is real, but it's mostly media propaganda to keep kids from realizing that it's actually very fun. Alas, I've been involved with some very shady people in relation to GHB, while it has positive effects on my mood, I will not argue whether it should be legal or not.
My Experience: I have used GHB now on and off for 6 months. I've spent a lot of money on it using it as a Body building supplement; pre-work out, post work out, alcohol replacement, meal enhancer, cutting enhancer, sleep inducer and stimulant come-down aid.
Messing with GHB the wrong way has lead me to being lied to, stolen from, jacked, other drug addictions and losing friends.
All I can say is that it's on another level of its own from AAS. Bluelight SD tells kids not to use AAS in their teens or beginning their weight lifting career. Renz says to use GHRPs or GH/ fragments, do not use GHB.
GHB can cause a complete different level of dependence and detriment on your BBing career and life. After using it, the withdrawals will eventually happen worse and worse making it harder to get off of. The "Liquid ecstasy" effects will wear off within a couple of weeks which require one to keep a gradually increasing dose, thus causing more severe withdrawals.
I recommend it over alcohol, however due to its positive effects, short half life and subjective better euphoric effects, it is a dangerous tool in the tool box.