Summering: Got this for work mostly, although nowadays I use for just about everything commuting back and forth (by bike). It use to house the bulky laptop (and still does on occasion), but nowadays it's the tablet along with a few accessories, keys, padlock, and workout clothes. A few other supplies, cables, etc. Plenty of room and pockets/nooks to fit tons of things in. I don't know how they made this thing out of plastic bottles, but I'll take their word for it.
Summering: I've been using this backpack for a few weeks now and I really like it. THe lighter green interior makes it easy to see things (rather than a 'bottomless black pit' of a normal one. The handles are comfortable and easy to wear. There is plenty of room and it actually stays on my back when I sling it up there - rather than those that slide down and you have to fight to keep them there.
Summering: The backpack is quite small as other users have pointed out. However it holds my 14inch laptop nice and snug and seems quite protected. It fits nicely on the back and the material is high quality and does not feel like it will break easily. Using this daily for carrying a 14inch laptop, nexus 7 and a lunch.