I switched to Abilify from Risperdal about a year ago and for me, at least, it's been a great change. It was never prescribed for psychosis, just because it in combo with an antidepressant can help take a lot of the edge off of autism spectrum disorders.
In general, whereas Risperdal would make me incredibly sleepy when it first started kicking in, there's no such side effect with Abilify. In my experience, Abilify hasn't been associated with as much weight gain, either. Other than that, it works about as well, which is great.