Overall I am very pleased. Enough for me to support it.
My current pet peeve is the prediction and auto-correct. It is not very good.
I have tried probably all the keyboards our there. Usually I gravitate towards Swiftkey due to multilingual support (Hate having to switch languages every time). I also used the Google keyboard when I had Nexus and currently I was reasonably happy with stock keyboard from my Sony. It had a reasonable good prediction and supported more than one language at the same time.
The fact that some didn't predict accurately the next word wasn't a deal breaker, though probably helped me stick with Swiftkey for longer. But auto-correct has been good overall on all of them.
But Chrooma, I really want to love it because it looks solid everywhere else. But I have to be more careful how I type and that should be quite the opposite reason to have a 3rd party keyboard.