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 agree completely with everything David Chartier said in his post yesterday on How to fix iOS 8 keyboards—which is why I installed a bunch of them when iOS 8 was released, and quickly deleted them. They’re buggy, missing too many features, and quite frankly they’re just not worth the effort of using them.