Keep in mind that
1. Many of us have older iThings which don't run iOS 8 very well.
2. The first 12-24 hours, the iOS 8 will do a lot of housekeeping and updating, thus draining battery and causing sluggish operation. Put it on the charger, leave it on overnight, see if that helps.
3. Many are waiting for iOS 8.01 update to fix the inevitable release bugs.
Biting the hand that feeds IT
