i assume your talking about the glass tube with the spring valve at the bottom. they are awesome actually. you get perfect control over when you start and stop filling the bottle. never have to worry about over/under filling the bottle.
They are good only for few people. It is called beer tower. I recommend for you to buy a personalize beer keg it is much more good for groups or if you have a party. Beer tower is only good if you drink with your 3 or four of your friends.