The U120 bag is perfect for a day of being out shooting in the streets. As far as backpack style of bags, it's one of the most comfortable I've ever tried. The adjustable, padded straps make it almost unnoticeable. And, it is very contoured on how it lays against your back and I have to say it is just the right size for the female frame.
The overall size of this bag is great. It is very compact but still holds all that I need. It's so roomy there are times I could probably get by with the U60 or a smaller shoulder bag instead, but what the U120 offers is the slot for the computer. It is in a very padded area that has quick access. And the front outer pockets of the bag allow for me to keep my computer charger and cables neat and organized.