I had one in 1986...lasted for 3 years and was used almost daily.
Great gismo, but in those days you had to use the special bag that came on a roll. It wasn't separate bags, it came on a roll which was about 10" wide, sealed at both sides but open top and bottom. So you cut it horizontally to the length you wanted and then sealed one end, inserted your stuff then sucked out the air and heat seal the top. I can't speak for this new model but I am currently going down the route of mylar bags and a heat seal (don't need the vacuum).
I would recommend the system if you need to keep things airtight (especially as the technology is probably better now)
Cheers
Sack