I agree with the fluidity problem. It definitely doesn't respond as nicely as 8.4.1. I ran the beta for one day but I had to go back because of the performance and plus I still just can't handle the new font. It feels so foreign and like I'm jailbroken. Sure it's cool that the keyboard switches to a lowercase but it totally screws up my typing accuracy. I'm so used to how things are that little changes are pretty big to me. I might be one of those people this time around hanging on to the old version for a long long time! Or I'll just jailbreak and put Helvetia back on!
You can turn off the lowercase keyboard.