I tend to agree with Stravinskylover that it is important to be able to play a piece flawlessly 'slowly' first and then gradually increase the speed.
But remember, no one cares about a wrong note here and there if the music is good (I think/hope :p).
Not quite true, people would rather there were no wrong notes. That said, there are far greater sins.
Do I dare to ask what those might be...
Rhythmic failings, tonal failings, dynamic failings and a lack of point.