So, I just updated to DP 5 after running 8.4, and I thought I would give my keyboard insights. In short, improvements are few and far between.
- keyboards will slide in smoothly, but only if you stay in a single app and have already activated the keyboard at least once. Seemingly they are caching the keyboard more aggressively or something. Switching away from an app and then back to it will force the keyboard to do the same slow, jerky loading process we're so used to in iOS 8.
- Using an app that blocks third-party keyboards (1Password or some banking apps) no longer causes the system to remain on the built in keyboard when you switch over to other apps that do allow third-party keyboards.
- Initial loading of third-party keyboards is just as slow and jerky as it had always been on iOS 8. This means the first load after switching to an app.
- the keyboard is still prone to not appear in apps occasionally, or refuse to show up for spotlight. This seems to be no better or worse since iOS 8.
- Messages is still a mess. You are apt to end up with some threads defaulting to one keyboard and others defaulting to another. Also, If you lock your phone while Messages is loaded and has the keyboard displayed and then unlock it again, it will revert to the default keyboard every single time. Basically the same behavior as iOS 8.
- dictation still not supported.
- Still no third-party keyboard support when using quick reply while the phone is locked. I suspect this is an intentional security choice on Apple's part.
Obviously a lot could happen between now and the public release, but given that almost all of these issues date from iOS 8, I have a sneaking suspicion that iOS 9 is not going to give us the bug-free third-party keyboard nirvana we're hoping for.