I've used a friends', and can confirm they work well.
For us, to own one though, not interested. Too much plastic waste, too expensive upfront cost (I mean.... maybe they last 20 years? But I'm not convinced. Plus, like you said, the cost of bags).
I freeze wet stuff in freezer safe canning jars, and dry-ish stuff in ziplocks which I re-wash, or canning jars. Yes, some stuff gets freezer burn- we try eat up frozen green beans by Christmas, for example, and I just found 2 jars that got buried, and they were pretty frosty. But we ate them, they were fine, and if nothing else I could have thrown them in soup.
We don't have a problem with food waste by using cheaper and more reusable options, basically. Maybe if I had problems I would feel differently. We would have to be wasting a lot of food to pay for one, though. We fill our deep freeze every summer, and it is empty and unplugged by April-ish. I kind of figure that I ought to be able to eat anything I am "saving" within 9 months, and the last few odds and ends can fit in the refrigerator freezer. Using stuff up seems to eliminate a lot of the reasons to have one.