David Chartier sums up my feelings on custom iOS 8 keyboards so far:

As interesting as iOS keyboards can be, their initial implementation at the OS level is severely flawed. They’re cumbersome to setup, switching between them is needlessly tedious, and limitations make it difficult to teach users about keyboard features. As far as I can tell, all these problems require solutions and improvements from Apple at the OS level.

I only use custom keyboards that solve a specific problem: Clips, for copying multiple bits of text; KuaiBoard, for visual snippets; Emoji++, because it’s better than Apple’s emoji keyboard. Even with these keyboards (which I only activate when I need them – as utilities) I’ve been annoyed by the system’s tediousness in switching between them and lack of consistency.

I haven’t been able to stick with any replacement keyboard as my primary one. In the first version of iOS 8, keyboards were too buggy to be used as daily drivers, but even after fixes I can’t use a non-Apple one on a daily basis. I’d miss the system autocorrection, QuickType, dictation, and shortcuts that I’ve grown to know over the years. Hopefully Apple will soften its stance on what’s off-limits to custom keyboards with iOS 9. Personally, I quite like Apple’s keyboard – I just wish it supported multiple languages at once.