Yes, it does knock people out, and otherwise acts like a downer. Back when it was still legal in the UK, me and a friend bought a couple of bottles at a sex shop, drunkenly (we were 19 and very dumb) swallowed them in one go, and proceeded to destroy my bedroom, laughing like imbeciles and generally descending the evolutionary ladder quickly. Since then, I've only ever bothered with the very occasional small dose on MDXX comedowns (a thing of the past, now), and if I were to swallow a bottle on a bellyful of bourbon again, at the ripe old age of 37 with a benzo habit it the mix, it would probably kill me. It's much like all downers - safe enough if used moderately, occasionally, and on its own, but highly addictive and very to fuck up on.
A friend once swigged from a blastic, unmarked bottle of GHB after a long night of coke and booze, thinking it was water. Luckily, someone grabbed it away from him before he had more than a mouthful or two, but he blacked out, passed out after trying to dive into the fishtank and sexually propositioning a table, then went to work the next day, started projectile vomiting and had to be sent home in a cab. Combinations with GBL and booze/benzos sound like an amnesiac nightmare at best, with a high probability of emergency room visits or worse.
A capful or two, coming down from X, is quite pleasant, though it's been so long, and my benzo tolerance has grown so high, that I wouldn't bother with it now.
