Same problem here. Recently I upgraded my ipad mini non-retina non-cellular from iOS 7..... to iOS 8.1 (NOT 8.0.1!) I heard that all the problems of 8.0 had been solved, so I tried it. I used iTunes for memory reasons, the latest verison of course. Unfortunately I have nothing but problems since. It started with the download being very slow and even stopping. At the end the whole system hung itself up, Nothing went forward anymore, even got a time-out. Causing me to switch the hole system off. Then of course my ipad was completely corrupted, so I started again. My provider said my line was fine and my other devices worked well. So bad internet connection not the problem.
After several attempts I got iOS 8.1 downloaded. However, nothing but problems. Hang-ups of apps, even the appstore hung itself up. Switch off and on sometimes helps, not always. Very slow Safari: It takes ages before the letters on the screen become sharp and readable, Also, when I google and get the page of answers, the screen does not respond to my touch. I did several renewals of the set-up, which caused the necessity of reinstalling all my languages and keyboards, saved places in apps etc. I get fed up with it.
I had just decided I wanted the iPad Air 2, but if this is the system by which Applethinks to convince customers of buying their new products, i.e. by making existing products unusable, I'll think again before buying an expensive device that will become useless by the next upgrade in a year or so.
As a last resort I am planning to reset my ipad mini to the factory settings and then try to download the backup I luckily made. Hope that helps. But it is not the way I used to deal withAppledownloads.
Anyone any other suggestion?
I am terribly disappointed and I do not dare do try to upgrade my iPhone, other iPAd mini or my mAc and MAcbook to the new OS.