I was on it a few months ago. Overall it wasn't bad. It seemed to work with my Trileptal.
Though I still had seizures, they didn't get any worse. I only had one side effect. When I was taking it I was sleeping a lot more. It was like I had narcolepsy. I'd get up in the morning and take my AEDs. After I go sit down to watch tv, and within minutes I'd be fast asleep. Some time later I get up to use the bathroom. I head back to sit down, eat, etc. But within a few minutes I'd be fast asleep. In a 24hr period I'd sleep at least 20hrs.
Onfi was too relaxing for my brain. So I stopped taking it.
I was given this right at the start- not actually as an AED, but something to take and chill me out, or if I'd really bashed myself up and just wanted to escape the stress/pain.
I had same reaction to it as bigman- always knocked me out- but I never took it regularly, really was something to have now and then. Though it was usefull like that, I doubt I'd want to take it all the time :S
Don't want to freak you out- and you know we all have different effects- but I'd be carefull of benzos anyway. I take a sleeping pill now and then for the insomnia- and the tolerance build up is scary..