First, I noticed prediction lags. A lot. Especially if you type fast.
Now, please help me with this: 1. I don't use pinyin (Chinese input). I don't even have it enabled as pinyin. I use a different typing system (zhuyin system) and yet Swiftkey still predicts pinyin. But why? Why am I forced into this option? This leads to the next problem: Swiftkey likes to predict English words like "uber" into "uber" with an umlaut. This is equally annoying because the English word is not the same as the German word.
2. There's no way to tell where some special letters or modifiers are. For example, the German "ß?" Go ahead and guess where it's found without checking EVERY SINGLE KEY on the keyboard. And the Russian keyboard? I don't even want to start.
For a keyboard that is supposed to be convenient, it, somehow, manages to force you into multilingualism. What if I don't want to, though? I want to type in one language at a time for the sake of accuracy. This prediction really... kills.