I've noted that mine grips very tight and hard after wrapping around anything. If my camera is loose it is because I have I have not taken care in wrapping around objects properly.
The weak link could be the plastic ball joints. If one of these break then the tripod may fail on you. But I've noticed that the plastic is a good, thick, slightly bendable type that you see on toys for 3 year olds. The rubber grip rings on mine are still in good condition and have not begun to deteriorate yet.
So a positive experience so far for me for $15. I don't know how an original Joby may be better since I have not tried. Sorry to hear that yours' didn't go so well.
I've tested those cheap ones before and the head could not support my camera body and lens, it fell and luckily managed to catch it on time. After that I bought a SLR zoom and it is very stable. I'd still recommend to go for the original Gorrilapod, a SLR zoom is good enough.