I have the same on Cyanogenmod with the AOSP keyboard (Android's default). It doesn't do next word prediction nor does it seem to learn when I pick a suggestion (it doesn't prioritize it next time), and I'm constantly switching between Dutch and English.
There are plenty of keyboard apps that do this better (even the stock Samsung one was great at this) but the keyboard is a core component that I want to be able to trust. I'm putting up with the annoyances and going for open source here. Not saying that this is the way to go for everyone, but it's not just Firefox OS which has this.
> The navigation (GPS) works surprisingly well though!
Navigation is not synonymous with GPS. Which works well, determining your location or routing to places? If the latter, I'm curious: which map source does it use, Google Maps?