When I was taking too much lamictal, it used to give me horrible side effects. I had double vision, could hardly walk straight or see straight. I felt like my head was spinning. Sometimes I'd have to crawl to go anywhere. I couldn't even focus enough to read a book. If I put my hand over one eye, sometimes I could read things, but that was it. I'd just lay on the bed, shut my eyes and wait for the side effects to wear off, after about an hour or so. My "former" neuro had me on 1000mg daily though. I had to take it 5 times a day, just so I could stand up basically. I take 400mg now and have no problems, except maybe insonmnia. But I think every AED I've ever taken has done that, so I've just learned to live with that.
Pheno was still the worst for me though because those side effects were constant. They didn't subside after a few hours.
On pheno, I had trouble learning. When I was in 1st and 2nd grade, I was put in learning disabled classes. I stuttered so bad, I could hardly say hello. There were certain words, I just couldn't say. It was usually words that had two consanants together, like an "st" sound, "sh" sound, etc. I had a neighbor named Steve and I couldn't say his name. I got stuck on the "st" sound. All I could get out was "s". The school put me in speech therapy too, even though my parents told them it was my meds.
As soon as I got off of pheno, the side effects went away. I was no longer in speech therapy, no stuttering or anything and I was transferred back to my home school and put in regular classes again.