I have one and really like. I have hiked around the Wyoming mountians with mine and it feels better on my back than a two strap back pack. You can also get the side quiver for it; which I have but never used it. I only wished it had a few more small zippered pockets.
It 'kinda' has a waist belt. I'm not sure though if you could hang a seat from it. There are two snap clips about 5" apart and hanging from the bottom back of it. I assume you can get additional small packs to hang off from it.