I own a pair of Ortlieb panniers for my townie which is great for slow, gear (or grocery) laden rides but purchased this to have something waterproof for longer high-speed commutes on my road bike.
The initial build quality is excellent just as I had expected and the fit is absolutely perfect. The little foam pads conform to the shape of your back and the bag is rigid and tight enough not to flop around when you’re out of the saddle. It is built with the minimum of seams and padding (which can absorb water) yet does not seem to sacrifice comfort.
I like that it closes with a metal hook which won’t break like a plastic clip nor come loose when wet like velcro.
Ortlieb keeps the water out the same way they do with their other products: There is a semi-flexible plastic squeegee-like strip that you fold the bag around. Two or three folds, a hook, and you’re tight.
The engineers really pared this thing down to the bare minimum size for what it needs to do. I can fit a change of clothes (size 10.5 shoes with the heels at the bottom of the bag), a repair kit and a computer with about 5″ of remaining space which would allow for some computer accessories and a puffer coat/rain coat.
For what this is I’d be hard pressed to offer succestions for improvement. One thing I’d like to see added is the ability to adjust the vertical positioning of the waist belt for taller folks.
Otherwise, El Niño, the Madden Julian Oscillation, North Atlantic Oscillation: I see you!