This is exactly what I was looking for. I wanted a general purpose carry-on that I can use when I also have a check-in bag. This slips over the larger bag handle so I only have to manage one thing, and it's about the maximum size it can be without being too large to carry in this manner. Once I check-in my main bag, it's nice to have a rolling bag so I'm not carrying a heavy shoulder bag or backpack. And it's easier to deal with at security since there aren't a lot of compartments to dig through.
I usually carry my laptop and other electronics and sometimes a large SLR camera, and this works well for that. I had considered one of those "mobile-office" type bags, but they are very limited since you can't really use them for anything but a laptop and papers. This bag is simple, without a lot of pockets, so can be used for many different things. If you want more organization, just buy some small covers or organizers and throw them it.
I have a Dell XPS 15" laptop (14"x9.5") that just barely fits in the back of the bag (with a cover). The front opening is a bit smaller, so I have to put it in at an angle initially, but once it's in the bag it fits across the width.
The front opening is normally attached on the sides near the bottom so it tips forward but not fully open, but velcro and snaps can be easily opened so it can be opened all the way. It's a nice feature.
There aren't a lot of bells and whistles on this bag. It's a good general purpose bag and seems to be well made so I think it will last a while.
It's too small for me to use as my only bag (I have a bigger carry-on for that), but it is big enough for someone that packs light or for short trips of a day or two.