First hydration pack purchase ever and I have been very pleased with it. Easy to fill and clean. Use it on most mountain bike rides, but has also been great on commutes to and from work...has enough room to hold my iPad and more.
I ride road in NYC, VT & NH and have had a real issue with cramps on long rides in the heat. At the risk of looking like a geek with a CB on a road bike, I decided to give it a try, to see if I would on-board more water. In short, problem solved! These babies might not looks so slick, but they work big-time! I did the VT 6-gaps ride (130-miles and epic climbs) over Labor Day we and went thru 6 liters of water courtesy of my CB. No cramps! The only negative (other than looks) is the fact that you year some sloshing when you're out of the saddle. No issues with comfort (heat or weight on the back). It does make it more difficult to reach jersey pockets (middle one is off-limits).