@wingpig, it's big enough to fit my camera with its 500mm lens. I tend to put some bubble wrap in the bottom to stop rattle. There's one big main compartment, then a couple of zipped compartments at the front, and a laptop compartment at the back (pannier rack side) with a complimentary padded sleeve - I 'would' be worried about a laptop or tablet against the rack like that).
For smaller camera use I've just lumped the camera in a couple of times, but I'd be tempted to take the strap off a teeny crumpler I have and used that within the pannier bag.
Head turned by the New Look bags of course!
But I may make the same, ahem, 'mistake' as gembo and order a Union 34, given there's one sitting in my basket just now...
Oh, and for road dirt on the back of the bags, there is a flap which then swings and clips out the way so (allegedly) you don't get it on your clothes - not been out in rubbish weather to test this yet...)