I like this monster. I was walking home today and thought about the person in front of me getting snapped up into extradimensional space by one of those things. It is always the prostitutes and vagrants that get the short end of the stick,
That said I had to re-read the first description a couple of times and it does seem that the monster would be better if it did not require air.
Still something I wouldn't mind ambushing my PCs with. It will get my vote.