I ordered the large with some misgivings, as I read a review that said it was huge. It's not huge; it's just right. I'm a teacher and use it to transport clothes, water bottles and various items for the classroom that I wouldn't put in my briefcase. I love the top-loading aspect of it, and the seams all seem sturdy and tightly sealed. It's not hugely padded in the straps, so I can see problems if you were carrying it on your back for long distances, but from car to office and back is ideal. The front zip pocket is huge and I put three one liter Sigg- style water bottles in it then zip it closed. They fit with room to spar. It's large enough to fit shoes (probably its design purpose). There's only one other pocket on the bag and that's a decent-sized interior pocket at the top that zips closed (no flimsy, small Velcro close). My wife, who can't seem to get enough pockets on her bags, would want more. I love the simplicity and think it's perfect as is.
I live in Seattle and we have a ban on plastic bags here. I tend to forget carrying bags to do my shopping so having a backpack style grocery bag is ideal for here and for myself. The only reason i did not give it 5 stars is that the shoulder straps need to be wider.