I haven't tried it, but I've heard good things about it. A buddy at my gym used it and gained a ton... like 25 pounds in 1 month. I was surprised at how good he looked for how much weight he had put on. Basically, it works by activating the CB1 receptor (hence the name), which stimulates appetite so it's easy to eat more. I'm going to try it with my next bulk.
It's interesting, on the Invalid Link Removed website it says that it "slows down the metabolism." Of course, there are thermogenics that increase metabolism, but the opposite? I'll have to look in to that.