WetGeek it changed asteroid 'moon' Dimorphis's rotation around bigger asteroid didymos by 23 minutes according to the story.
As for ultimate effect?
"Focus now is shifting toward measuring the efficiency of momentum transfer from DART’s roughly 14,000-mile (22,530-kilometer) per hour collision with its target. This includes further analysis of the "ejecta” – the many tons of asteroidal rock displaced and launched into space by the impact. The recoil from this blast of debris substantially enhanced DART’s push against Dimorphos – a little like a jet of air streaming out of a balloon sends the balloon in the opposite direction."
Curiously absent from this story is the effect on the real bogeyman: Didymos. More to come, I'm sure.