(1) I have purchased so many of these units that I now count having (4) that are 5- units tall, (1) that is 4-units tall, (2) that are 3-units tall, and (1) that is just a single unit on the 360° wheels. I have them mostly in white but I did get a 4-unit one in black. Black looks more dramatic.
(2) I love them! I live in a small apartment and these stackable, mobile storage containers allow me to be very organized. The give me flexibility because I can easily move them around when cleaning. And I can stack them however I want because each container has its own lid. Each one also has four small hidden wheels that move right and left. And, four of the 360° bigger wheels come with the set you purchase.
(3) The 5-unit one in my kitchen holds extra pots, pans, spices, utensils, bowls, collanders, etc A 4-unit set by my desk keeps books and rotating organizers with craft and sewing supplies inside it. Another 5-unit stack holds my sewing fabrics, batting, and interfacing materials, and embroidery thread. Clothes are in a 5-unit white one in my bedroom. Two 3-unit stacks hide in my closet; they hold sheets, blankets, winter coats and sweaters, pants that do not currently fit me...The single unit one fits under a table or I can slide it under my 18" high platform bed when I want. And, by my bathroom I have a 5-unit stack that holds medicines, toiletries, cleaning supplies, and medical equipment.
(4) I really like being able to see what is inside them easily. They are easy to clean: I just use a cleaning spray and wipe with a paper towel if they get dusty.
(5) For years I have been the Queen of Plastic Bins, keeping everything organized. But, the old style bins can be heavy to lift and you can't always see what's inside them easily, or access one at the bottom of a stack without lifting all of the ones on top to get to it. This new style changes everything!! They are fun to use. They are sturdy. It is best to put heavier items on the bottom or lower stacked bins to balance them better. They are very good as to move around. I highly recommend them!