This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.
Convenient and simple for light and small loads. You can't get an
easier way to carry the camera and phone. But for heavier loads, and
longer rides, most people will prefer other systems. Larger fanny
packs are made, but for riding most people find they are less
comfortable, due to ventilation issues. Stability and control are
generally not an issue. If you can load it in the pack, you can
probably safely carry it.
C. of G. Very Good
Stability Very Good
Ease of Access Very Good
Typical usage: Short distance/around town, commuting, day
Weight capacity: Up to 5-7 lbs. would be typical.