Keeping a field journal on weather conditions, game sightings, successes, failures and your musings while on stand is almost as rewarding as hunting itself. It can help you lay your plans based on previous days in the field, and reading about the time you killed that big 8-point because you switched setups in the middle of the day to account for a northeast wind helps fill the offseason with happy thoughts.
I pack my journal with me into the woods, and as such, it receives a lot of abuse. Pages get wet, muddy, even bloody. A $1 notepad won't cut it. For the last three years, I've been carrying Rite in the Rain All-Weather notebooks. Developed in the 1920s for loggers in the Pacific Northwest, their heavy-duty pages are virtually waterproof. Yes, you can write on them in a downpour if you so choose. Try that with your smartphone.
They come in several sizes, but I like the small versions because they don't add much to my pack. A 1/4-inch "universal" grid printed on each page helps you draw maps and sketches to scale, as well as divide pages into neat columns.
A handwritten journal may be old school, but the hard-earned notes contained within will remain long after a cell-phone contract expires and takes stored data with it. Rite in the Rain notebooks are made to last as long as the memories written on their pages.