I have used musette bags since I was very young. I tried other backpacks but the simplicity of a musette bag takes all of the thought out of packing for hikes, trips, hunting, etc. It may even make a good emergency gear pack. Plenty of space in the main compartment, plus the side pouch for some energy bars or a first aid kit and the rear panel has a thin pouch that's as tall and wide as the main compartment, that perfectly fits a map or poncho. The eyelets on the flap (originally used for holding an entrenching tool when issued during WWII) works great for strapping a hatchet or machete too.
As much as I love it, the reason it doesn't get a full 5 stars are because 1) It isn't waterproof canvas. 2) The strap buckles aren't good for quick access. 3) It isn't meant for heavy duty gear hauling or long trips. A few days or more at most, or possibly ultralight backpacking. And 4) The straps are also very thin, so to carry the pack comfortably it needs to be rest near the mid-back, much lower than most classic packs.
All that said, it's a lightweight, durable (tear resistant), easy to use backpack, and that's why I own 4 of them; Two jumbo sized and two standard size, in black and olive drab each.