This is a quality lumbar pack. I recently purchased a North Face Roo Pack, which I deemed to be too big for typical walks, hikes, or runs. The North Face Roo Pack didn't seem to be built as nicely-- I really like the ventilated cushioning on the back of the Mountainsmith Vibe II. It's not too big, fits about right. The clip for the strap is to one side (the left side if you wear the pack facing rearward or right side if you wear facing forwards), whereas most similar packs put it in the middle of the strap (i.e. the way the North Face Roo Pack does). The nylon strap feels sturdy, not too narrow and not too wide. It has good organization in the main compartment: 3 open/mesh pockets, plus 1 zippered mesh pocket, and a key chain retainer clip. I'd estimate the main compartment to being about a half liter in volume (this was important info for me to know based on what I plan on using this for, but I couldn't find that out anywhere until I bought one), since a typical half liter water bottle could just barely fit in with the zipper pulled tight (but I probably wouldn't recommend ever carrying a water bottle in there-- it's just a size estimate). The front pocket is very nicely cushioned for a pair of glasses, plus it has another mesh pocket for an MP3 player (iPod) with a covered headphone opening. The zippers are nice and don't rattle. I loaded it up, put it on, cinched it up, and ran around with it-- only minor bouncing around, it feels comfortable for jogging.
If you're thinking about getting a lumbar pack (a.k.a. "fanny pack") but you think you're too cool for one (don't want to look like a tourist or like you're European or something), there's a strong possibility you could get all the usefulness out of this one and wear it under an untucked shirt and nobody would ever notice-- not true for many larger packs.
Overall it feels very nicely constructed and compact. It's a bonus that it's made from recycled materials, but I wouldn't have bought it based on that alone. The North Face Roo Pack is going back to the store, which is fine by me, because on sale it was $10 more than this one anyway!
Oh, and Amazon Prime shipped mine fast-- ordered Tuesday afternoon and had it in hand on Thursday afternoon. Thank you!