Today, my iPad Air quit updating apps. It would show the updates were available, but the app downloads were perpetually stuck on their "circle" updating.
It turns out the issue may be the WSJ app in Newsstand. Deleting that app, then restarting updates let them proceed at their normal pace. It seems to be an issue in the app itself, since reinstalling WSJ again blocks app updates.
There are reports this blocks anything related to downloads from the App Store and iTunes.
Thanks to the discussion over at https://discussions.apple.com/thread/6548849 for the hint