I used this pack for training for a marathon on trails around Colorado. I found that it:
1- Has enough capacity for between 20 and 30 miles depending on the dryness of the air and heat level (obviously the two will determine how much you drink)
2- Fit nicely once I had a few runs with it and got used to cinching it down correctly
3- Only gave me chafing when I let my shirt ride up after a few hours of running
4- Held ample gu's and gels

My only complaint would be that the side pockets are way to the side and near your back so sometimes it's hard to get something out of them while running.

I had high hopes for this pack -- Camelbak seems to tout it as a 'minimalist pack designed for adventure racers.' Well gee, that sounds nice -- I run marathon+ distance (primarily trails) and am notorious for carrying along little more than a hand bottle for hydration. Perhaps this will be the solution yo my dilemma.

Well upon taking it for a test run today, it would NOT sit still. Even at a very conservative pace it was bouncing all over the place. I tried almost every combination of cinched up straps, loosening them, dumping water, etc. The bottom line is the webbing is too flimsy and the buckles don't like to hold. It through my pace off and I had a frustrating run.

It MAY work for some people who run extremely slow or don't mind a constrictive bag of water bouncing up and down on their shoulders... but as for me, I will be returning it and sticking to waist-level bottle-holders by amphipod or some other brand instead.

I use this for running and I find the belts do exactly as you want them during the run. The container has enough room for ice for those long runs during the summer heat. It has enough space to keep a few fuel gels or bar, money, etc... I am very happy.

Went on my first run with this pack this morning. Initially, I was a bit apprehensive as I've never run with anything like this before, but I was really surprised and impressed with its functionality. The shoulder straps keep the pack high up on your mid/upper back and the chest and waist buckles help lock the pack down and not bouncing around all over the place messing up your stride. The side pockets weren't as difficult to get to as I thought they would be while running, though I don't think any pocket is big enough to store a rain jacket in (unless it's a REALLY thin jacket)... but they are big enough to store a change of UnderArmour-thin underwear/shirt and socks. The back panel has chambers that help air circulate and keep you cool. The bladder was full, yet the pack didn't feel heavy to me. Overall, this pack will definitely help with my 4+ mile runs... I'm very happy I got it. Now, if Backcountry.com will honor my 50% off coupon that I got in my email two after I ordered the pack, I'll be in Camelbak bliss!

This is my third, and easily my favorite, CamelBak. First, it should be noted that I use my CamelBak while snowboarding, so to buy one of their products which wasn't winter specific was a little counter-intuitive, but it's PERFECT!

My first CamelBak was too large. I couldn't lean back on the chairlift comfortably. My second CamelBak was too small. It was comfortable, but it didn't hold anything except liquid. This bag, on the other hand, is absolutely what I've always wanted. Putting the storage pockets on the side allows me to put snacks and stuff in there without adding any distance between my back and the chair. It's exactly as comfortable as my smaller bag, but far more useful.

As for the lack of insulation, I wear it underneath my outer-most layer, and have never had a problem with freeze up. In fact, doing it this way even allows me to thread the waist strap through my pants' belt loops for an extra snug fit which doesn't move at all.

The CamelBak has gotten me through three 14-plus mile runs. I'm able to carry enough water to get me through the run, plus have enough for my warm-down walk.
The pockets on the side are good for carrying gels, but can be a bit tough to open while running.
If you get the air out, the water won't slosh around too much while running.
And it's certainly than trying to manage the bottles/belt option.

If you are hearing sloshing noises that means you aren't prepping your CamelBak bladder correctly. After you fill it up turn it upside down and let all the air out via the Bite Valve. You shouldn't hear sloshing anymore and it should feel nicer against your back. If you are having trouble with it being stable, you need to work on getting the correct tightness going.

I tested this pack for the first time on a 14 mile trail run today, and loved it!

I found it extremely comfortable - it stays wonderfully snug against your back, and it didn't move around at all. The padding is really comfy and non-sweaty too. The narrow design is also great for keeping out the way of your elbows so they don't rub against the sides! I REALLY like the side pockets in the waist strap too, which are perfect for keeping snacks readily accessible. The stash pocket on top is great for keys etc, as well.

I'm a lass of average build, and although the straps are clearly designed to accommodate larger shoulders as well, the chest strap keeps everything in place, and my shoulders didn't ache at the end of the run at all. The chest strap did dig in a wee bit, but at least it is designed to take account of the female form, sitting well above the girls rather than squishing them!! Happy me.

The ONLY drawback I had on first trial today was the amazingly distracting slooshing of water in the bladder, which spoilt the running karma a little at first, but the sloshing lessened as the run progressed. Surely possible to expel the air better next time - I'm told that if you turn the bladder upside down, once you've put the water in, and open the mouth-piece, you can squeeze most of the air out that way.

Overall a really great Camelbak, down to the last cute details.

I got this with the intentions of road running. The main draw was the capacity, which will allow me to run up to 20 miles without refilling. The 2 biggest drawbacks are:
1) pretty loud sloshing noise while running, but you get used to it;
2) when filled to capacity, the bladder doesn't sit flush against my back.

Otherwise this is a good option for holding my phone, gels, and keys when I run.

So far so good. I can live with the sloshing, your carrying 72 ounces of water, what do you expect? The pack is easily adjusted on the fly as you use up water and want to tighten it. The quick adjustments are also nice being that I like it a bit looser on the climbs and tighter on the descents. As far as this being for only "slower" runners, I'm 16-17 5k'r and it works very well with my training pace but I only use it for my long slower 2-4 hour runs. Who runs 5:30-45 miles with any kind of pack?

I have been using this pack for about 6 months now, and it works. It only bounces around if the pack is loose, and thats the deal with any pack, if its a hand bottle, waist pack, or a pack on your back. If it bounces, tighten the straps.. Done. Since I use this for my long runs on trails and eoad running, I would have liked it if it were a 100oz pack, and had a bit more space for food. Overall I would recommend this pack. Side pockets are great for holding gels, bars, and electrolyte tabs...