My only main issue with Windows Phone 8.1 is actually the very thing that is making it desirable to new users....Microsoft is being forced to Cater and thus sort of make the OS redundant.
Case in point...we now have the action center(notification center) but it is so redundant because I already have my live tiles. yes the feature is great to have and it is something people have been calling for, except, it makes the live titles seem useless now which was the defining feature of the OS.
I do miss the Centralized hubs we had with Windows Phone 7 and Windows Phone 8......Where the social networks were properly integrated with the OS without needing to rely on Apps as the functionality was built into the OS.
However, I realize the benefit of Microsoft dropping the hubs because it truly slows the development of the OS down when you have to update every aspect vs making thing decentralized which means faster updates(and frequent).
Cortana > Google Now > Siri
Overall, Windows Phone 8.1 is great and unless you are a heavy app user, I doubt you'll have issue adapting(I dropped Android in 2012) and even so, the apps are there(or suitable alternatives) @DRE