Some people love Gabapentin and have few side effects. As an add-on to other AEDs it reduces seizures, and addresses neuropathy if someone has that as well. Bonus, better sleep.
Some people hate it. They have reduced cognitive function and are sleepy all the time. It really screws them up. Some people the side effects wear off or get somewhat better after a few months.
Some people it has no effect whatsoever, in which case the doc usually raises the dose before tossing it altogether.
The key to whether to be scared of a drug or not is to look at the package insert and see what the common vs. rare side effects are, and how serious they are. When looking at the percentage tables, look at the DIFFERENCE between the drug group and the control group (that has no med).
If the control group has it in 19% of the people, and the drug (experimental) group had that side effect in 20% of the people, that means that side effect is only happening 1% more in the people who take the drug than those who don't. Not a big increase.
Here's a link to the NIH (National Institute of Health) website with gabapentin's package insert:
http://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=13041
Gapapentin is a pretty old drug, too. Lots of time for long term side effects to pop up and be recorded.
I'm one of the ones that happen to like gabapentin. But I'm with you. Meds really mess with my body, even changing doses can screw me up. Be sure if or when you try the Gabapentin you add only this one thing at a time. Start with a small dose and ramp up slowly.