The binding in the Kokuyo is twin ring, which means there are two rings for each hole in the paper. This creates a strong spiral that resists being deformed when put in a bag with other large objects. I always hated how my notebooks in school would exhibit a harsh slant in the spiral binding after a couple of weeks of class. With the Kokuyo notebooks, this isn't as much of an issue due to the smaller diameter of the spiral, and the extra reinforcement. As another bonus, the double spiral also means there are fewer accidental tears. It seems like single spiral notebooks loose pages more frequently because it's easier to rip them out.
The front of the book has two covers in a way – a semi-rigid translucent front cover, and a normal cover with the branding and information just after that. I'm assuming the translucent cover on the front is to add a bit of protection to the book, but I'm confused as to why there's only one. Why not a little protection on the back? Given the price, it's hard to complain.
So, it's a notebook that you write in. How does it handle inks? Really well.
This isn't a premium paper, so you can easily find notebooks that feel smoother and handle show-through much better, but you'll pay much for them, especially if they are similarly sized. The semi-B5 size is a great step up from the standard 5.5" x 8.5" notebooks that are really common. It's not so big as to be unusable on small desks, but it's also quite spacious.