With top open
Here you can see a belt loop. The stitching is very rugged and secure. On the lid portion you can see a zippered compartment (silver/grey area in picture). The black tab looking thing is a leather cover that covers the zipper when the compartment is closed (so the zipper won't scratch your camera). That's if your camera sits that high in the first place (mine does, as you'll see later). This compartment is quite shallow (I don't use it), you can fit memory cards and or lens clothes.
Inside the bag
Here you can see the inside has two support "dividers" that can adjust to the width of your camera+lens for a better fit. On the underside of the dividers are elastic loops (one on each divider) for you to hold something small like batteries. The velcro that holds the dividers in place is very strong and doesn't detach when support your camera. Well, more accurately, it holds my Canon 400d with battery grip securely.
Here you can see there is a pouch on the front of the bag. This pouch is rather spacious, however just because it can expand a lot, the zipper won't close at max expansion. A 430 EX with Stofen Omnibounce attached will fit in this pouch (zipper will close)