I have a few different hydration packs that have served me well but nothing like the M.U.L.E. With the version of the Camelbak bladder and the wide range of adjustments this pack offers, it might just be my favorite pack. Its small enough to use when I go Mountain Biking, but adjusts to be able to carry a big load when I go on a day hike...it's like a trusty little load toting mule that wraps itself on my back holding all my valuables safely.
The thing I like the most about this pack and what differentiates it from the others I have had is that its comfortable under load, has loads of features, straps, adjusting, and has cool removable hip straps if you don't want them dangling down and it doesn't have any harsh edges that dig into your back as you pedal or hike.
Get yer hike on!