...SwiftKey. It's available on iOS as are many other third party keyboards although admittedly the integration isn't great. As for voice input iOS has had that in the built-in keyboard for 3 or 4 years.
Yeah, but all iOS Keyboards have serious stability problems. I'm sure that it's Apple's API's fault first, and hope that MS's resources help iron things out, but its really frustrating.
Integrating Cortana into the keyboard could be interesting though, would like to give it a spin if more convenient than it is today in comparison to Siri.
You're right the integration of third party keyboards is awful. I spend more time trying to get the right keyboard to show that actually using the thing.
