This pack is the best daypack I've used. It's nice and light, fits tightly to your back and is well ventilated. I use this pack nearly everyday in the summer for trail running and it's perfect. Features that are especially well thought out are the magnetic hydration hose holder which keeps your water out of the way as you bound down the trail. And the dual hip belt pockets make it so you rarely have to take off and open the main pack compartment. The hip belt pockets are big enough for an energy bar, camera and a map.
The pack seems small and is best for those who know exactly what they'll need, as there's no space to overpack.
My only complaints might be the sometimes unecessarily big 3L water bladder (2L is my preference) which often causes the annoying water splashing effect. Also, despite being light, the pack has some over the top feature. For example, the hydro bladder compartment both zips and buckles closed and there is no need for load bearing straps over the shoulders on a pack this small.