For my 640xl this is definitely downgrade from 8.1 Yes,it looks nice,there are more features but what's the point if with all the good stuff comes all that bad stuff and good one doesn't really matters anymore. I don't know where do i star? I've sent so many feedbacks about bugs and lags that i even don't remember all of them. I'll just point out some major issues. Phone is sgnificantly slower now,some of the apps might even take 10 secs to open. If previously i charged my phone basically once in two days,now i usually do it twice a day. Rich capture is such a mess. First of all,even my old LG L9 is capable of taking better quality pictures. Second thing,camera app often crashes,somitimes it takes forever to save a picture,even if i exit the app and go back it still shows that it's being saved.for some of the pictures you can't adjust lighting,it gives you some kind of error. My phone even decided to restart few times and after that i wasn't able to open notification and action center. All these problems usually happens when i try to use rich capture. There are problems with many apps. Fitbit,for example,can't be used at all. Let's say you're tracking your excersise. You lock the phone,unlock and when you try to use app it crashes,no matter what you do. Even if you restart your phone and you want to start all over again you won't be able because it will say that you already are tracking your excersise. And there is more than that,these are just few thing. From loving my 640xl,i soon might start to hate it,seriously...