It takes a while, but it works. The longer you are on it the faster it gets because the more connections you get.
Starts off at 5 days, goes to 7 hours... In reality it would probably take 3-4 hours at most. Probably less.
The nice thing is that you don't have to sit there and monitor it!
Also it's a nice thing to do. You share your bandwidth so that single servers don't get hammered.
Plus leave it up, so I can download it faster, too!!!
Just think of it as a nice nod to the developers and to those that share the bandwith with you. It realy helps out with this sort of thing. Otherwise (like when slackware 9.0 came out) people have to wait 2-4 DAYS to get a proper download from the overloaded servers.