The first generation Newton was insanely good at recognizing really terrible cursive handwriting and terrible at recognizing tidy or printed handwriting. The second generation Newton was very good at recognizing tidy handwriting (and you could switch back to the old system if you were one of the freaks whose handwriting the old system grokked). The Newton also had really nice correction system, e.g. gestures for changing the case of a single character or word. In my opinion the later Newton generations recognized handwriting as well as you could expect, when it failed you forgave it and could easily correct the errors, and was decently fast on the 192MHz ARM CPUs.

Speech is way, way harder.