Mine is the Topsider brand, metal tank (therefore non-collapsing unless driven over), and has worked fine for six years. It's changed oil on two different boats, cleared that last little noisome bit out of a marine holding tank annually for fall layup and been able to be cleaned itself afterwards, drained Seadoo bilges and cruiser bilges both, and sucked several gallons of water out of the bottom of a cruiser's gas tank (please don't ask). The seals are still good after exposure to a variety of uses never intended by the designer, and it holds more than my 560SL oil sump does.
One of the more useful ways I've spent the 45 bucks or whatever it cost, and one of the things I've bought that actually worked as expected (and better) and keeps on doing so.
'97 SL500, 40th anniversary edition
'04 Olds Bravada (SWMBO's)
'06 Lexus ES330
'89 560SL (sold)
SL--Anything else is just a Mercedes.
(Kudos to whoever said it first)