Great lightweight pack, no muss no fuss, easy fill and cleaning, and no weird aftertaste if the water sits in the bladder for a day or two. The bite valve seals up tight to keep out dirt and pops off for cleaning. The pack itself is light and low profile, great for bouldering or biking or trail running. The reflective strip shows up in even the dimmest light. Best basic hydro pack out there.
I use this for trail running, mountain biking, and during rescue work. It's great because it is incredibly low-profile, with only a small pouch good enough for my car key, some snacks, and one or two other small items. It's super-light, too. The only thing I wish it had was a chest strap, because for whatever reason climbing with the pack tends to push the straps apart.
Obviously CamelBak is the big name in hydration bladders, so the bladder itself and mouthpiece work great as expected. I have another of their packs that has more storage space. I got this one because the low profile lets me wear it without notice while doing rescue work. It actually fits really well under a PFD during water work (just remember to tighten the straps on your vest as you drink). It doesn't hold much stuff, but that's not why I got it. If you want no frills, just water capacity, then this is your pack.
My girlfriend got this for me as a gift recently since I am training for Worlds Toughest Mudder and will be going on longer runs than usual. Ran with it today for the first time and loved it. It's very light weight and you really can't even tell it's there. I used the adjustable strap pull-strings as a chest belt, but it stayed pretty snug even without doing that. All in all, great product and can't wait to train with it again!
Just got this pack for a "Tough Mudder" competition I've participating in next weekend... As with all Camelbak products, this is a high quality hydration pack, but this particular model is somewhat no frills with not a lot of room for storing your stuff. Perfect for running or biking, especially since it's day-glo yellow color ensures you'll be seen by cars in dusk lighting. Also, it's lightweight, which is one of the reasons I picked it up for my upcoming race.
I find the 50 oz size to be great for bike rides. The 100 oz is great for hiking but on the bike I prefer something lighter. It will get nasty if you don't clean it regularly... especially if you use Gatorade instead of water. It is easy to wash and I recommend never leaving any water in there for extended times.
This much improved over carrying clunky water bottles around on a day hike. The 50oz capacity is perfect for a few hours out. The straps are fully mesh so they stay cool and breathable. I like the bite activated nozzle which makes it easy to partake of water or whatever else you decide to pack along. A compact design and a HUGE filling port makes it easy to clean out and fill. No plastic-y taste, but do recommend the cleaning tablets or a water/baking soda solution to keep it from retaining smells or coloration. A nice find!