This XS messenger bag replaces my large shoulder strap fanny pack, whose zipper began to fail.
The good:
Spacious:  Enough room for 3 or 4 Kindles or IPad minis, if that's all you want in there.  But not an iPad.
Sturdy:  Constructed of heavy materials.  Heavy shoulder strap.  Waterproof lining on the inside of the flap.
Secure:  Velcro and snap closures for that belt and suspender approach.  The heavy strap would be hard to slash.
Suggested Improvements:
A handle at the top of the back panel.  (There is a handle at the bottom of the front panel, but picking up the bag by that handle would turn the bag and its contents upside down.  What were they thinking?
Exterior pockets for quick access items; an open one on the back panel and a zippered one in the front of the flap.  As it is, the flap blocks handy access to the contents, except for a "Napoleon" pocket useful for, say, a smart phone.
Get those clips and swivels back on the strap.
Overall, a useful personal bag for one who prized function over fashion.