I own all four sets (Chapter 1: Paper, Cotton, & String; Chapter 2: Nectar + Pollen; Chapter 3: Arboretum; and Chapter 4: Spa), and each one captures a different sensory experience.
I love everything about these sets, but the only one of the scents I can't abide is "Moon Shadow," which is the second sent in Chapter 4: Spa. The predominant note in Moon Shadow is jasmine, and while I don't mind that note in other fragrances, in this version, it's just sickening to me.
My favorites are Chapters 2 and 3--I find myself reaching for those more often. However, Chapter 1 is very springtime-appropriate, and Chapter 4's Kirimashi Air and Root are very nice, too. But remember, beware Moon Shadow! :D
What makes these sets fun is that the scents are very unique, and each box comes with a little pencil and notebook for "Field Notes." I feel like a little girl every time I open one of the "chapters," since the packaging is so whimsical. The vials of perfume make me think that Margot Elena was an explorer in some fairy land, and that's how she came to collect these lovely scents.
To store the cases upright, I have them resting in-between two bookends on my perfume table, an appropriate place, wouldn't you agree?