Ive been tempted to go back to 8.0 on my Lumia 920, but was stopped because they don't let you.
Ive had to install UC Browser because the new version of IE doesn't display the Desktop version of a lot of the sites I use. My battery life is now crap since 8.1. A lot of the features don't work like Folders on the main screen & Cortana. Apparently I need to wait for more updates for these. Ive been very tempted to switch phone companies & go back to my Lumia 800 ...
Basically it took a really good phone & gave me a half arsed update & I feel like Ive gone backwards 3 years ...