First, the compact keyboard (in T9 mode, of course) will select the correct word (if one exists) for all of the keypresses in a sequence. But if I go one keypress past a valid word, it automatically reverts all of the characters in the word to the first letter of each key. For example if I type testing, it guesses the following for each key pressed:
t
ye
yes
test
testi
testin
testing
But if I accidentally press another key, say 'df' it changes the entire word before it:
teatubgd
That can be really confusing. It should show the longest word it can make, plus the extra letters, like:
testingd
Second, compounded by the behavior above, it is impossible to spell out words which are not in the dictionary. I have to either turn of T9 or switch to the full keyboard. This can be fixed by alternating between the first and second letter of a key if I press backspace and press the same key again. Say I wanted to type some nonsense word like "blag". With T9 enabled, this is not really possible. The sequence looks like:
b
bl
bla
blah
And if I press backspace and the 'gh' key again, it just spells "blah" again:
blah
bla
blah
But if it were smart, it would realize that if I press backspace and the same key again, I must have wanted the other letter on the same key. So the sequence should look like
blah
bla
blag
And there is the word I want.
