I like Camelbak, but...
I have been a Camelbak fan for a long time. I have played with generic reservoirs and they don't hold a candle to the camelbak quality, but I have had trouble with this specific piece. I love the idea and they start out great, but after two failures with the hydrolock I'll avoid it.
After a lot of use one of them began to leak from from the yellow valve. Without much use at all the other piece became completely useless when the yellow valve became so loose that it would just fall out while walking, causing the water to gush out in its place.
The whole concept is to prevent water from coming out when you don't want it to, but I have found that I leak more water with the hydrolock than I do without.