I use this bag to carry:

--Nikon D90, usually with a 16-85mm lens attached, in the camera section. I could easily carry a much bigger camera here, though I can't really comment on a battery grip.
--70-300mm lens (with hood on backward) packed horizontally in the bottom section..
--35mm prime lens in the right middle, opposite the camera. I pack the 16-85mm here (with hood) if I have the 35mm on the camera.
--SB-600 flash in the top section, positioned just as pictured in the Amazon photo.
--Spare battery, flash cards, and lens caps in various pockets.
--Battery charger in the top zipper compartment while I'm traveling. I leave it in the hotel room once at my destination.

With all the above (minus the charger) packed, I can comfortably carry one or two bottles of water and a few snacks in the top compartment, plus a water bottle in the side pouch.

The bag itself is comfortable to carry, and I love the quick-access zipper. Everything feels sturdy and well secured. I didn't feel the need for a chest or waist belt like some other reviewers, but I can imagine a smaller person might like one for longer walks. And I'd pay more for some kind of breathable material on the back pad.