Very handy when packing winter clothes or some unused pillows and duvets.
These bags are really big so takes some effort to fill them up. Also even though there is the pump included I prefer to use hoover as it is quicker and more effective. I guess pump is a "nice to have" thing.
As per some negative aspects - I noticced that one bag was slowly getting the air so might be a small leak somewhere. Also I think that it would be better if package would have mixed size bags.