Light, cheap, no "plastic-y" flavor to the water, durable (over 4,000 miles on one), folds down tiny when empty. I carry 2 1-L for hiking and a 12 ounce one for my night cap.
A cap from a 2L soda bottle can be used instead of the squirt cap.
Narrow mouth and non-rigid sides make it hard to get water from non-moving water sources (like lakes). You have to do a scooping action or use your cooking pot to fill it. Not a biggie.
Flexible, light but holds great capacity for drier stretches. At my job we have platy tanks which don't seem to zip closed at ALL, so the security of this bottle was a pleasant surprise.
