This Field Notes Expedition edition after a two and a half months trip. Everyday in my pocket for fast notes. It's almost unbreakable. It's supposed to be waterproof and other crazy-proof. The thin notebook is perfect for the pocket and replace my usual little organizer for travels (mainly because of the thickness).
Writing on such a plastic surface is weird. Only a few pens can be used, for example ball pens.
Next time I will experiment with a similar format but filled with my dear vergè paper, a pleasure to write on it. Probably it will not last this long but maybe it ages in a beautiful way.