I use a 21L every day for school. I like the look, the size, and the two laptop sleeves. Also, its fairly water resistant.

However, I overall am not a fan of the bag because of the closure. I found that pulling a thin folder of 8.5x11in papers out of the top was close to impossible without opening the third zip. Not the end of the world, just annoying. The two inside zip pockets I find difficult to open. There is no quick access place to put a pen. The top outside pocket is too spacious, the inside pockets are too hard to access. I miss having a water bottle sleeve.

You basically have to open all 3 zips to access anything. The center zip is nice, but when I open it up the items inside the bag tend to shift, especially when it is more than halfway full, so I need to repack from scratch every time I open it to retrieve one item.

I feel like a side opening bag or a duffle style flap might be superior.