It's plenty deep enough! The bag can hold quite a lot, I find. My laptop is about an inch thick, and I can carry it inside the brainbag, plus a few texts and notebooks, all in the same section. (The two main sections are identical in size).
So say I use the compartment closest to my back for a laptop, how deep is the other main compartment? I need to carry around my digicam cases, which are about 3.5 inches deep or so. I can stuff them into my current pack, but they get squished quite a bit.