I would have thought things would have gotten better after a week of iOS 8 being out. I am trying to download iOS 8 for my iPad Air. Currently (at 7:30pm EST), the download time is estimated at 24-40+ hours. Anyone else having this?
You might want to wait until the successor to iOS 8.0.1 comes out (and wait a few hours for the dust to settle on any showstopping bugs before installing the update). That way you can install the OS plus all the bug fixes in one step.
And after today, you might want to do the update using iTunes (seemed that the issues primarily cropped up on OTA updates) and a wired connection. Even if Apple's servers are slammed, you can just let iTunes download the update file and use your iPad like normal until the download finishes.