I've been running with the pack between 3 and 12 miles, and in some ridiculous conditions. Pack kept everything dry, and had some great moments where it felt comfortable on the run.
Only reservation - it's a tough fit for tall people. I'm 6'3, and the waist belt is difficult to keep...waistward. It tends to cinch up, and then everything starts bouncing around. I've ended up just tying a drawstring around the belt which works (when I have a drawstring).
Would be nice if there was a pocket you could reach when running - I was wearing a headlamp and didn't want to stop to stow it (or the wet gloves).
With that said, all my stuff ends up dry and the ventilation works well (didn't feel sweat building up along the back).