I have experimented quite a bit with them. For some things tehy work real well, for others not so much. One of the problems is that while you save some vertical space, you end up with all this useless extra plastic flap you need to take care of. One trick I have found is to use the really large bags, and pack as much as you can into those, and then compress it all at once. I am going to post a few Amazon links so you see what I am talking about, but you might find some better prices elsewhere if you search.

First things first, get an air pump. These will get you much better compression. This is the one I use, has held up for a year and a half so far, though I am starting to worry that I am getting a little rough with it.: . I tried one of those foodsaver batter pumps, but they did not work.

I use the Travelon Bags: . I like these because they have a vacuum pump port, but also can work as roll up bags. Plus, I like the thicker more flexible material (more a vinyl than plastic). You do have to be a bit more careful about sealing them, however, as they do not have a zip seal.

I have some Eagle Creek bags , They are OK, they seem durable. I like the zip seal, although i have lost a few of the little plastic zip sealers. The problem with these is they are hard to get all the air out, so you end up not getting as much compression. And, the plastic is not as easy to fold, so you end up with a lot of extra plastic to deal with you cant easily fold.

Lately, I have started to use the Foodsaver Quart and Gallon size vacuum bags for underwear and socks. This has really been helpful - I can put one days worth in a bag. If you are real careful about placing it in a bag (don't just stuff it) with the hand pump it compresses real well, and has the double bonus of being easy to organize. One hint, put a little piece of paper with dirty written on it when you reseal the bag with the dirty stuff in it. The one problem is I find the zip seals aren't terribly good. The Foodsaver so far has been better for me than the ziplock brand.