Messenger-style bags, in my experience, aren't a great design for camera bags. They tend to be big, which makes them easy to overload, and that makes them uncomfortable and awkward to use. That's not the case with Timbuk2's Informant Camera Sling.
The Informant isn't a pure messenger bag, like those that Timbuk2 is best known for. It's also not the typical camera sling bag, which tend to be backpacks with single straps, or a regular shoulder camera bag.
It has elements from all three bag types, though, which is probably why it works so well. The Informant comes in two sizes -- small ($99) and medium ($119), which is the one I tested -- and both are designed to be worn across your back like a messenger. They both have a tough nylon strap with a compact cam buckle for one-handed adjustments.
A big cushy shoulder pad is also a carryover from Timbuk2's messengers, as is the durable ballistic nylon construction and the included removable cross-body stabilizer strap, which helps keep the bag from flipping around when you're riding a bike.
It even has the traditional front flap of a messenger bag. Or, at least, that's how it appears.
Unlike on a messenger bag, there isn't one big flap secured at the back covering everything inside your bag. On the Informant, it's sort of one big flap secured at the middle, basically covering two separate compartments. The top half covers the main storage compartment, while the bottom half (or front) of the flap covers two large storage pockets in front.
The left pocket has an organizer inside for a phone, pens, keys, earbuds, or whatever else you want to jam in them. The right side is just a big pocket, which, while testing out the bag, I used for a sling camera strap.
The flap is secured over the pockets with a strong hook-and-loop closure, so it'll keep big things from falling out, but anything small you'll probably want to put in the main camera compartment. Also, the closure is really loud and there are no silencers. If you're taking this to an event or someplace where you need to be quiet, I wouldn't store anything essential in these pockets.
On back, which would be the part against your body while wearing it, is a zippered pocket. It's a good place to stash the included rain cover; the nylon can handle minor splashes or a brief period of light rain, but for full-on downpours, you'll want to slip on the cover.