iOS8’s introduction of custom keyboards is one of my favourite features but like so much in this release it is very buggy. I’m not sure if the issues are with iOS or the keyboards or a combination of both but they are frequent.
Some of the issues I have encountered are:
1. keyboards not appearing
2. no words appearing when I type
3. no button to change the keyboard appearing (and not just in passowrd fields)
4. keyboards appearing all over the place (see below)
I’m sure that all this is fixable but right now I would describe the custom keyboards as alpha at best.