I had the keyboard on two phones in use and there were no problems.
The keyboard learns from the input and from existing SMS, Gmail, Facebook or Twitter, if desired. Thus, an individualization for the user is given. The inputs go faster, because after a short time, the hit rate of the prediction is high.
Only the adaptation leaves something to be desired, the layout can not be changed, but colors.
In the privacy policy, I could see that passwords no detection is performed and otherwise the user will not be spied superfluous.
Absolute recommendation on my part.
By the way a credit to Amazon for the Amazon App Store, which works without a credit card and a rebuke to Google .... Service desert Germany, no one wants my money and I have no credit card .....