I am heaving the same problem but in this case is rather exemptuated; i live in dubai and in order to use facetime i need a vpn service which i regularly use with facetime and Skype through my ipad mini retina display 2013; the problem started after i upgraded to iOS 8 and then it got worst after the 8.01 and then the 8.02 upgrade, it claimed to fix some bugs but unfortunately it worsen my performance; when i set the vpn on and then use the ipad it constantly shows a grey screen with the words "Poor Coneectivity" and it remains that way for the whole conversation, it is gruesome, i did reset my device and to make matters worse it didn't want to download all my apps from either my itunes nor through my iCloud backup, it was from bad to worse, after i got that settled it still remained the same "poor connectivity" issues as well as the wifi dropping as well as the data, and it claimed that my data and wifi were off when it wasn't.
At first i thought something is not right, not even the iOS 7 did this when it first came out; and today i realised that when i picked up my ipad it was frozen sideways as if i tilted it (when read or watch videos for a better perspective) and i noticed that the lock rotation icon was not turned on and it was locked in that sideways position; i had to reset the ipad and then it started to work again fine except for the facetime, which by the way bluetooth also gives me issues.
the only way i could verify my ipad's status was for me to use my iphone 6's facetime and it worked fine, the tilting the audio as well as the bluetooth; the only issue my iphone 6 gave me was that the wifi and data would suddenly come out asking me to connect to a wifi or turn on data for facetime use etc and it would try to reconnect; which is the same issue that a lot of people are facing with the ios8 upgrade and the latter upgrades were said to fix that particular issue but it didn't.
i am worried and i don't know if my ipad is going through hardware issues or its only the iOS setbacks that came with the upgrade, any ideas, thank you.