For the past few years, I've used packing cubes for travel. But this unit is an improvement on the concept. It's simply amazing that one can lift out shelves and hang them.

Pros:
1) Shelves are well-balanced and hang well when packed.
2) Super easy to pack and unpack.
3) Zipped compartment keeps small items from spilling.

Cons:
1) Small version is a tight fit for some carry-on bags.
2) Packing cubes ultimately give more space if space is important.

I would recommend the smallest size even for a larger bag. The extra space can be utilized for all the odds and ends that travelers pack, as well as a soiled clothes bag.