People taking this drug for seizures are going to have very different experiences then the bipolars, I believe. Pretty much everyone has some weight gain, but not major (10-20lbs).
I was diagnosed as a rapid cycling bipolar, and before this drug, I was completely miserable. I was started on Depakote instead of Lithium due to fewer side effects, and it was a huge sucess.
Moods are stable, manic episodes are gone, sleep is stabilzed, libido is normal, depression is rare. I am 20 lbs heavier, happy, and "normal". I can't say enough good things about this drug.
Bipolars, steer away from the negative comments here and go to the bipolar support sites. You will find almost nothing but positive testimonials about this drug for our condition.