I've been looking for a bag for a while that could handle my home life (with 4 kids) and be presentable enough for the office, AND be able to comfortably carry my (heavy) Kindle Fire.  This bag fits the bill perfectly.  The fabric (black) looks both casual and office-worthy, the pockets are legendary, and the zippers work perfectly.  My Kindle fits perfectly in the slip pocket behind the interior zipper pocket (fits better than the in the Extra Small).

I initially ordered the Extra Small, but being 5'8" the shorter length of the body of the bag did not fit well laying against my back when worn cross body.  The strap cut uncomfortably along my side and across my chest.  This size works MUCH better, and I can totally feel a lighter weight with this bag compared to other ones.  The Small is just a tiny bit larger than the Extra Small, mostly in height rather than width, but this difference is huge in terms of comfort for a taller person.

Since this bag is larger than I needed on a daily basis to go to work, I picked up a Large Baglett to use that I clip inside the Small when I need a larger bag (ie. when going out with the kids and/or when brining my Kindle).  I also tried the FUL Ditty, but that didn't work for me (see review).

This bag is fantastic!!  And, you can't go wrong with Amazon's great prices and awesome return policy.