I was on Valproic acid before and couldn't tolerate it either. Too sleepy and weight gain (although I'm very active and have an eating disorder so I really really can't tolerate either of these side effects). It worked well at controlling my mania though. Not so much the psychosis, but like Miguel'smom I have schizoaffective so my psychosis is separate from my mania/depression.

I've done well on just an antipsychotic alone (clozapine). Right now I'm on two antipsychotics and two mood stabilizers though because clozapine requires a lot of blood work and the system here just isn't adequate enough to deal with what that entails (and it causes massive weight gain and a lot of sedation).

If you've been on the valproic acid for more than a month or two and the side effects are still bothering you and you haven't gotten any benefit from it, I would say it's not worth it. But that's just me.