The first thing I noticed when looking at this pack is that it's really well put together. Everything seems to be of the highest quality, and they've obviously put a lot of thought into the details. For example, the way the bladder is fastened to the inside of its compartment to keep it from jiggling round while you run.......
This pack fits very nicely on my back, and I find it quite comfortable to run with. I didn't really get any side to side motion or up and down jiggling.
I'm not sure if this pack has or is being discontinued, but they seem to be going for a really good price from what I've seen- less that $50. If you can manage to find one, I think this would be a great option for hydration for longer runs where you want to be able to carry a bit of gear with you.