I enjoy this pack very much. I have a little trouble with retrieving things out of the zipper pouch while running but this a trivial problem because its just as easy/fast to stop get what I need and go on. There is plenty of room for my GU, cell phone, and iPod. I have not used it for runs longer than 13.1 miles, but the liquid capacity is good for that distance.

I've run with several lumbar packs but have found this one to be the most user-friendly (I don't hate it). I am kind of pear-shaped (or "hippy"; I'm a women's 8 up top, and a 10 below.) but this pack stays put better than others. It still rides up a bit, but I can tighten the straps easily while running. The fluid capacity is a little small for runs longer than 16 miles--I had to refill halfway for my 20 miler. Ample storage for snack, keys, cash/ID, cell phone. It is difficult to retrieve snacks from the zippered pockets without stopping. Clips on each hip hold the water line in place, and there is a stay to tuck straps into so they don't flap in the breeze. I can sip and stow easily without breaking stride. If you expel ALL the air from the CamelBAK bladder and avoid allowing airleak into the bladder while you run, then it is SLOSH-FREE.

I bought this pack for long trail runs and almost threw it off a cliff the first time I used it. It may be the best pack ever for hikers, bikers, and male runners, but if you are a female runner with a waist, this pack is balls. When full of water, it either bounced like a jack rabbit or bruised my hips from being cinched too tight. If the last thing you want to do on a run is stop every ten feet to adjust a pack, don't buy this.

I got this pack for a 34 mile trail race....it worked great. It was comfortable and was big enough to hold my essentials for the day.

Use this pack to jog up a mountain trail and it works great. The pack fiets snug around my waist and doesn't loosen along the way. It's easy to use while jogging and allows me to keep stride without interruption.