Switch to Keppra?

My husband has had epilepsy for over 19 years.  He does not have a "defined" epilepy.  Even his epilepsy specialist can only define it as "most likely primary".  So he has always been a "blanket" anti-convulsants - that cover primary and secondary (most recently Depakote).  He had been regulated for the last 5 years on 500 mg of Depakote daily.  He had a grand mal seizure recently, followed by another one 59 days later.  Both times they increased his Depakote to the point where the side effects make it very difficult.  The hair loss and weight gain are tolerable - the short term memory loss is not.

We went to see his epilepsy specialist (the one who got him straightened out over 5 years ago) and he feels that he is as regulated as he can be on the Depakote.  He made the comment that drugs have gotten better since 1978 when they introduced Depakote.  I asked what he would recommend and he said Keppra.  My husband, at first vehemently apposed switching meds - it is always a nightmare - is now contemplating it.

For those on Keppra or who have switched to it, what are your experiences - bad or good?