Why I still use a paper notebook
Recording apps are excellent and I use one at home to tidy things up. In the field, though, a pencil slows me down in a useful way. Writing "small brown bird, pale stripe over eye, flicks tail" makes me look for the next feature instead of reaching for a menu.
The notebook itself is nothing special: pocket size, waterproof paper, elastic band. The elastic band matters more than anything else on a windy dike.