It took just over an hour last night for my 3 apple devices to update.
The iPod went without a hitch, that's only on iOS 6. something though. The ipad took ages, at first I kept getting an error message saying something like unavable to verify download, when it was trying to install. It did eventually work ok though. The download took aaaages, possibly because their server was busy? I didn't have any way of checking what speed it came down at. The actual update, once it was finally happy with the download took about 10mins.
Because it was taking so long, I thought I'd turn on the tv and look for something to watch. Doh... Up popped a notification saying the Aptv needed updating too. This failed and then kept saying there was no internet connection.. And I also got several notifications that it couldn't find iTunes on the network, which it wouldn't
Out of interest I just checked my bandwidth usage last night in Plusnets usage panel... 5.74GB! I did stream one prog last night, but even if I allow a generous 1Gb which should more than cover my normal bandwidth bearing in mind I've no pc... That's one heck of a lot if bandwidth for anyone on a limited or capped account.