I swear by mine. We have
Amazon Basics ones and they have gone on many, many trips and still look/ function like brand new.
I use 2 medium sized ones each for me and DH. I can generally pack each kid into 1 medium each (or 1 medium each for day clothes and 1 medium for pajamas for all 3 together). I have a large one I use mainly for diapers. I like the mediums and smalls best because they're easier to move around in the suitcase, and they also fit easily into a carry-on bag.
Pros:
-everything is neat in the bag (less wrinkles)
-you can unpack by putting the whole cube right into a drawer
-easier to sort clothing by person or by day, whichever you prefer
Cons: everything fits so neatly, it's easier to over-pack (not necessarily a "con" but still I'm amazed at how much I'm able to neatly fit in a cube)
I don't know if it helped or not but we've had suitcases checked by TSA and everything was left neatly in cubes how we had packed it. It was as if they were able to take the cube out, see what they needed, and put it right back. It was nice to not have it all rummaged through and unfolded etc. Had we not had the notice from TSA I would have never known they went in there.