A large flap covers both the main camera compartment and a large front pocket. The accordion fold on the front pocket gives you some extra space for accessories or even a secondary compact camera. It doesn't have a zipper, but there is a large hook-and-loop strap to close over the pocket for a little more security.
The main compartment is designed to hold a camera with lens attached in the center, with room for an additional lens and flash unit off to the sides. According to Think Tank's site, it can hold a Nikon D700 with a 24-70mm f2.8 lens attached, a Nikon 70-200mm f2.8 lens, and a Nikon SB-900 Speedlight.
The bottom of the bag is fairly well padded and the included padded inserts can be customized for your needs; Think Tank includes a few additional inserts for even more flexibility with the layout. At each end of the bag inside are two collapsible nylon pockets that are tall enough to fit flash units, each with a strap to keep it tightly closed.
In the front of the compartment is a shallow nylon pocket that runs the length of the bag with a tethered clasp for keys, as well as pockets for business cards and pens. In the back of the bag inside there is a large zippered pocket, too. It can't hold anything too bulky, but since it's a soft-sided case you do have some room to play with. It's well suited for cables, extra batteries and battery chargers, memory cards, or other small accessories.
It just would've been nice to have at least one of these located in the front pocket; with the bag full it's not always easy to get things in and out of these interior pockets. Also, there's no place to attach a tripod, so bear that in mind if that's a necessity for you.
Large hook-and-loop closures keep the top flap secure when the bag's closed. If you're shooting somewhere where a loud tearing sound from the closure might be unwelcome, silencers on the inside of the flap can be used to cover the hook-and-loop straps. It means the bag's not as securely closed, but it allows you to get in and out of the bag quickly and quietly.
Also on the inside of the main flap is a small pocket for business cards or ID or, you know, whatever you can fit in it.
The Think Tank Retrospective 7 has plenty of room for a day out shooting with or without a small laptop or tablet. But it's not so big that you'd feel like you had a hulking empty bag on your back if you decided to travel light. It's well-constructed, too, and the materials all seem like they'll hold up well over time.
It would be nice if there were a small zippered pocket outside for quickly stashing something like a phone, but the large back pocket is sufficient and it's a minor point on an otherwise excellent bag.