Shorty review time! I bought these cubes ages ago on my first trip through Europe. I used a suitcase with wheels, and these cubes worked marvelously to keep my clothes organized.
I got the three size cube set. The largest cube held jeans, dresses, pjs, socks, and bottoms. The medium cube held teeshirts and other tops. And the smallest held undies and other small items.
It worked really well to roll and pack my clothes, as seen above — I could fit more and keep more from wrinkling as compared to folding and stacking normally.
I originally brought the cubes on my second Europe trip, but they didn’t work too well in the backpacks — rolling without the cubes worked much better. So I’d recommend them for suitcase use, rather than backpack.