I used and loved this bag for a year and a half. It fit my Canon 40D with grip, Canon 70-300 IS (non-L), Canon 18-55 IS, extension tubes, charger, and medium Giottos rocket all in the main compartment. The top compartment had enough room for small accessories, the rain cover (very useful, and included with the bag) and maybe a sandwich, but not much more. I like to be able to carry all my photo gear plus laptop, water bottle, food, and even a rain jacket if necessary. This bag simply didn't have enough extra room so I upgraded. I love the side-access and different possible strap configurations (which was why I initially bought the bag). However, the bag sits rather low on the back, even with the straps at their minimum length, and I found it somewhat uncomfortable during long hikes.

Advantages: Side-access, different strap configurations, decent amount of room for photo gear.

Disadvantages: Not much room for things other than your photo gear, gets a bit uncomfortable when worn for extended periods.