I had one (by choice) and it was the best decision. Baby was back to back and I'd been in labour with him for about a day. Every time I had a contraction I would vomit, so the epidural allowed me to sleep and actually have a drink without throwing everything up 5 mins later.
It has to be administered by an anithetist so it may take a while for them to get you sorted if the hospital is busy.
My legs felt abit funny after the birth - but it took a few hours to wear off.
You can control how much of the drug you use, so you can still feel the process of pushing the baby out, but if the pain gets too much you can administer some more drugs.
Once they had done the epidural, they basically allowed the labour to develop at its own pace. My waters didn't break - so they eventually broke them. So I didn't have my baby till the Monday morning (epidural done Sunday evening)
My sons now 9 months and I've had no adverse side effects.
I wouldn't hesitate to do the same again. Don't feel like you need to rule it out. Some hospitals allow you to walk around with it, some (like mine) don't, so it may be worth finding out there policies. Personally I was happy to sleep so walking around was right at the bottom of stuff I wanted to do
. I'm also sure your not allowed to have a water birth with one in.