If you are stuck at 10% downloading, don’t fret, this happens occasionally, and it usually isn’t player-side. For whatever reason, Blizzard’s download severs are occasionally funked up when a patch releases, and are offline, sending all of us into mad rampages
This WILL resolve itself, so everyone don’t get your panties in a wad. Right now, it doesn’t look like there is any time estimate on when we will be able to get the full download, but for now, you can visit: http://www.wowwiki.com/Patch_mirrors for a download on a mirror site.