Lots of space, with numerous different zippered storage areas, including semi-hidden storage. I use it to carry lunch as well, and one space has a pocket where I put an icepack for keeping items refrigerated (I add another, larger icepack into a plastic bag to protect the actual storage place, and then put the food items inside the plastic bag into storage space.)
I mostly use it with the rolling feature, which is very sturdy and useful, and sometimes carry it in my hand with the small carry strap on top. My only problem: to use the backpack option, to sling it over your back, is awkward, difficult and uncomfortable. The collapsible handle (for use with the rolling option) makes the whole thing feel very hard on the back, and the backpack straps do not adjust sufficiently to accommodate my somewhat portly figure.