As near as I can figure from the articles, the merits of the book itself, and not any cultural phenomenon that grew up around it are:
0) handwritten/human-read (some consider it a merit, some a demerit, some a "don't care")
1) graph paper instead of lines or blank paper
2) an entire year (it looks like 1 page per day) in one book. Can be used as a datebook, bu doesn't have to be.
3) nice binding
I do like graph paper. I do think it's much more handy than the alternatives, and allows for clean text, lines, tables, drawings, etc. I find it also makes indentation and formatting more repeatable, so you can develop your own layout for a page that makes certain things jump out at you upon review without needing to resort to an * ALL CAPS, TWICE THE SIZE * -- IMPORTANT! style of note-taking.
Still, I think the graph paper may have a broader appeal the Japanese than others. I think using the Latin alphabet means that you'll get less out of the same space than your Japanese counterpart. Having one-page a day is also probably too little for some work, too much for others. I tend to go through a 100-sheet, 5-squres-per-inch composition books in about 2.5 months of light note-taking, so I'm having trouble imagine shrinking things down into a single book.
EDIT: angle brackets, arrows, and exclamation points are a prime example of what not to use to markup things if you don't want it to look like HTML and get it tossed out upon validation. Changed my example so it's just annoying caps instead of annoying caps + symbols.