I bought one several years ago, as others stated I found I only used it for a long ride where stores were not well placed along the route. The small pack allowed me to carry more food and my full wallet. However I don't like the way it feels on my road bike. With such little use it developed some mold on the inside. Cleaning resulted in a damage bite valve which I replaced twice.

For hiking, which I now do a lot of, I have started using a water bladder as well, I like this better and use it more. I went with the Platypus brand, I think they are much higher quality than camelback.