I got one recently and love it! You have to freeze anything you want to seal first. It pulls a suction and will make a frightful mess if you try to use it with unfrozen liquids.

I freeze liquids in plastic freezer containers, then take them out of the containers and put them in the food saver bags. It sounds like a lot of work, but it isn't. For freezing cooked solid foods (I make lots of casseroles), I put them in the food saver bags, then put them in the freezer standing up until they are frozen, then wipe any moisture away from the inside of the opening, then seal. I've frozen cake slices the same way - freeze first!

It's a real life saver, believe me. I don't use it for things that I know I'll be using soon because of the expense of the bags, but do for anything that might be there for a while. And things take up a lot less space in the freezer when they're in those bags.

Go for it!