I purchased this bag in late June and wanted to wait a bit before writing a review so I could put it to the test.  I primarily bought it to use for outings - festivals, the Zoo, etc., where I needed to carry money, ID, a camera and water but didn't want to have a purse to deal with.  This has been just perfect!  I holds my wallet if I want, sunglasses, reading glasses, my camera and keys and fits perfectly across my body without being in the way (or too heavy/bulky) once I got the strap adjusted to my height/width.  And having a place to put a bottle of water that is easily accessible (esp during this hot summer!) has been great!  I've taken it to the Zoo two or three times, used it at fairs and church festivals, etc.  I can walk around with it, sit with it on and it even handles the Tilt-A-Whirl.  So far I haven't had any problems with wear and tear.  I highly recommend this if you are looking for an alternative to carrying a purse.
UPDATE: August 11, 2010.  I still love this bag.  Just took it to the State Fair and it was so nice to be able to walk around with my hands free and have a water bottle right there.  Still no problem with wear and this bag gets used almost every weekend.