I make a lot of mini albums and they're usually a rather time-consuming affair. This die really makes the whole process quite simple, and most important at times, fast! You can put together a small mini-album in less than two hours, whereas doing that without a die is next to impossible.
It's a clever design which is also attractive and adapts easily to many different styles.
I used it three times so far - twice to make small journals with water colour paper pages, and once using felt on the inside to make a needle book. Just make sure that you use a material that is not too thick or the crease sections along the spine may cut instead. I used a thin chipboard, or reused cardboard, like from cereal or cracker boxes.