I bought this for mountain biking and hiking. So far I've used it for mountain biking and love it! I'm 6'5", about 200lb, and the pack fits great. It can adjust to fit someone smaller and larger. I'm impressed with the overall quality and the design of the hydration sleeve and valve design. There is plenty of space to carry keys, wallet, sunglasses, a small lunch,and a few biking tools. I liked it so much that I ordered the women's Dakine Session (Skyler) hydration pack for my wife.
The biggest win for me is the robustness of the hydration sleeve and hose. I went over the handle bars on my bike and slammed on my back. I got up and checked the pack...no leaks, no tears, no problems. Overall great quality.