Say what you will, but I will probably *never* get used to using a soft-keyboard on a mobile device.
The vast collection of websites with people screwing-up messages (AutoCorrect, Windows devices notwithstanding) bears me out.
Also, it just doesn’t feel right, what with the lack of physical keys, &c.
The best keyboard I have ever used is the Microsoft "Natural" ergonomic keyboard. It takes a bit of getting used to, but once you are comfortable with it, you will never willingly use anything else.