I just did the update. Downloaded the file with Firefox because i was having a problem with Safari (it was unzipping the file) and everything worked smoothly. It didnt take that long for me and i was able to backup in iTunes. Currently i am syncing and getting all my data back.
There is a preference in Safari in the 'Preferences' menu to 'open safe files once downloaded' if you have this selected then it will extract any zips, etc once you have downloaded them