They work fantastically - some of the time. Given they're reusable and effective, I would say they are definitely worth the expense. Just make sure you get a reliable brand - it's their durability that makes it worth while.
They have worked really well for our family. We live in a condo and need all the room we can get. They are great because you can put them under the bed and in the closet. Give you alot more space.
Space saver bags initially work well, but in my experience, I haven't found one that works for very long. Also, if you have a cat...one little hole from a claw and it's all over.
In my experience the more I use space bags, the less they work. The seals become worn and they eventually blow back up to the normal size. But at first they worked great! If you have the room I would go with plastic tubs.
