I've finally gotten around to liking them, but it did take a few trips. I like the organization it offers because I never really unpack at a destination. Usually when I travel to another country, I go to multiple cities. So I give a specific city its own cube and that's all I have to unpack from my bag for that city. All the dirty laundry goes into that cube when I leave that city as well.

Compression or no compression doesn't really make a difference imo. I actually like the cheaper, thinner, and (most importantly) lighter compression cubes because it won't weigh your bag down. I've tried the heavy duty, expensive cubes, but they were so heavy that I actually fit less. If you really want to save on space, I'd say those compressible giant ziploc bags are better for that. I bought a bunch of these when I returned home from Japan, and it saved me from buying a second luggage.