This happened to me as well. I called Apple and was with tech support for about 3 hours. The first thing to do is uninstall all components from your computer. There is a specific order in which to uninstall, so make sure you go to apples site and look that up.
If that doesn't fix your problem... You'll eventually get an error message -5000. This error does not exist yet. (I was the first one to have it) So the techs are working on it and there wil be an update sometime this week. They know it ***** and apple support is SOOO nice. If you absolutely can't wait (like myself) try using another computer. That's what did the trick for me.
Now... I also had issues with that, in I would get error 3194 (which does exist, don't worry) but I couldnt do anything to fix it. If this happens for you:
When you plug in your device click "later"
make a backup of your device first
Then click the "restore" option; this will restore to factory settings and the run the update without saving a backup
I had to use both my computers to do this, because magically... What didn't work on one worked on the other
after that, it worked fine
If you don't have 2 computers and don't want to use someone else's all you can do is wait. I know it ***** BELIEVE ME! But apple is working as fast as they can. The thing is apple update and windows update came out at the same time. So thy weren't prepared. (I have also tried uninstalling all my windows updates and restoring my computer to an earlier point, but to no avail) They are doing their best, and it should be ready within a week.
Hope this helps/gives y'all some hope!