When I was a geology student, we had to spend 6 weeks on a field camp, during the summer, most of it in western Utah. I'd carry a 2 liter plastic bottle (i.e. a pop bottle) in my pack. It'd start out full of water each day and most days, I'd return to camp with the bottle empty and needing a drink.

Now granted, at the time I was not the smartest, and I've learned a great deal since. One day, fairly early in the day, I dropped my pack to check out an outcrop. The outcrop was a key to the assignment so I spent quite awhile there. When I got done, I picked up my pack and it was wet, weighed about 3 lbs lighter, and there was a wet spot where it was sitting. Apparently, when I had dropped my pack, a rock had punctured my bottle, right on the bottom and it was empty.

I learned something that day: "one problem with the [bottle system]: one leak and your whole supply can be gone."

Now fortunately, I could get to where I could get another bottle and some more water. Later went to Nalgene bottles, which are much more durable (but would have been pretty expensive while I was in college).

Eventually, I broke down and bought a bladder system (a Jansport that was $20 at a Sam's club). I loved it and have since replaced it. I still carry a Nalgene with me as a backup if I'm way off the beaten path but I primarily rely on a bladder now. Before I had one I could not imagine myself with one. My office neighbor, who is a hardcore biker, finally convinced me to try one (and obviously I went the cheap route to try it out). Now I cannot immagine being without one. I even bought youth ones for my kids (I added a whistle and a garbage bag to theirs so that they have something with them and they love to go hiking because they get to wear their "water packs").

Anyway, a bottle will work, but it can fail. A hydration pack can fail but it is much more convenient than a canteen because I constantly sip at it and rarely ever get thirsty.

Also, I learned today that I have a disability because I too have a hard time holding onto my walking stick (or rock hammer or rifle, etc.) while removing my pack, digging out a water bottle, opening the water bottle, and drinking it. I used to overcome this disability by putting down my walking stick (or rock hammer or rifle, etc.) but I got sick of backtracking to retrieve it. So, I like the hydration pack because it minimizes the effects of my disability and even if it is considered "so 'cool'; the latest toy", I'll stick with it.