Like any healthy pen addict, I have quite a collection of notebooks. You never know how you'll like a particular notebook until you buy one and try it out for a while. For me, one of my favorite notebooks to carry around and use is the Clairefontaine 1951 Collection books.
There are several things about these notebooks that I love, so let's start there. Paper quality is one of the highest priorities when selecting a notebook, and the paper used in these notebooks is exceptional. It's bright, silky smooth, and well-behaved with every ink I've used. I have not seen feathering or bleed-through. Show-through is very faint on the back of the pages. The paper is described as 90 g/m^2 weight with acid-free properties. Overall, the paper has never disappointed me.
Another part of the paper that I enjoy is the ruling color and spacing. The line color is a light purplish-gray that really stays in the background when writing. I've used some light-colored inks on this paper, and the lines do not overpower the ink. For me, the line spacing is perfect, but this is one of those details that will vary for each person.
For some, the fact that these notebooks are only available with lined paper is an automatic deal breaker. I completely understand and wish that Clairefontaine offered more options. I happen to like using lined paper for some things and find that the spacing in these notebooks is perfect for my journaling or long-form writing style. There's no index or page numbers - just the lined pages.
The book has been very durable for my usage, which is limited to being carried in a bag every day with other objects. The cover reminds me of a composition notebook, which is a plus for me. The diamond pattern is subtle but distinct. There's a Clairefontaine logo and a cream rectangle for labeling the book. The rectangle is about 2x4 inches. The book measures in at 5.75x8.25 inches, which is very similar to many of the “medium” journal options out there.
I'm not in love with the soft cover. I prefer hard covers on my notebooks so I can write in my lap or on uneven surfaces without worrying about my paper not being flat or stable. With that said, this cover is durable and wears very well. Bound by two staples, the notebook has a little trouble staying flat on its own, but a little breaking in will fix that quickly.
The last thing I'll mention about these notebooks is the price. They're very affordable for the paper quality. You can get them at a better deal from JetPens if you buy 2 at a time, and they offer a nice range of pastel colors (black, blue, green, pink, coral, and turquoise).