Bought this for my boyfriend. He loves it. It hold more than enough water for a day hike (not exceeding 14ish hours). It may look small but it manages to carry quite a bit and still fit comfortably on your back. I would definitely recommend this bag if you want to keep the luggage light but need enough water to get your through a full day hiking/biking.
I was looking for a quick summit pack, and I found it with the Osprey Viper. It holds a ton of water, and has enough pocket space to store gloves, food, and jacket. It has a great comfortable fit, and it weighs next to nothing. More importantly it doesn't get in the way when I'm making my way to the top.