This is a good bag - very sturdy and well-cushioned, and it does a good job of protecting my gear in the rain. (I unfortunately got caught in a downpour, with a tiny umbrella, the first time I took it out.) I have a D40, which is on the smaller side, and the bag fits that, the kit lens and my 55-200mm lens, as well as the lens hood. (I should note that I have folded down the top part of the divider between the compartments, as it goes up too high and gets in the way.) I do find that the strap can get uncomfortable after a full day of carrying this around messenger-style, so a cushion may be in order.
The bag has some interior pockets, including a mesh zippered pocket on the inside of the flap, good for small/flat items. The pockets on the front are hard to get into and the hidden pockets on the side (where the strap meets the bag) might as well not even be there. The front pocket (under the flap) expands open a bit, and within that is a mesh pocket with a velcro closure. This is practically useless as the mesh is flush to the bag and the velcro is pretty tough -- I can slide in a skinny moleskine notebook, but wouldn't put anything smaller in there for fear of being unable to get it out without pliers or tweezers. There's enough room in that front pocket for a magic/Jacob's ladder wallet and a small keyring. Luckily there is enough room in the rest of the bag that I can slip in some tissues for allergy season and a tiny travel bottle of sunscreen for the summer.
I am not a gal who likes to carry more than one bag if she can help it, so was looking for something that would hold all of my gear, plus the basics of wallet, keys, etc. This barely fits that bill, but I was afraid that the next size up would be too big. Obviously if you don't take a second lens out with you, there's more room for all this other kind of stuff. But if you travel light (or make sure you always have enough pockets in your pants/coat/etc) this will do you well.