I had 'mobile'epidural, basically it's just a low dose one, I believe it's the standard one they use. I had lengthy emails, requests etc to make sure I got it, with the head anaesthetist at the hospital (in Belgium)..
So came the day, I had it, BUT was still monitored etc by horrible junior doctor, disobeyed her and got on to hands and knees etc.
It was definitely a bonus as I had a very long 36 hour labour, and it took a lot of the pain away, BUT NOT ALL! I have to say that a low dose one does not take all the contractions pain away and I still had pain, but the plus side is that I could push fine. However, had no pain at all on actually crowning/pushing the baby out, which was great.
Make sure if you want it that you ask for it in advance, you make it clear you want to move around (walking is not really realistic as you are hooked up to a UV and the epi itself and you get paranoid about pulling it out), and get into different positions etc. Also make sure how long the epi tube is. Mine was only about 1 meter, so not long enough to get very far from the wall, so they scupper you with that..
I found it a very good choice as legs weren't numb, you can push OK although pain is by no means all gone, it was very painful, but I'm sure not as bad as natural, but it is very unlikely you will actually be able to walk with it, and believe me I really tried!
best of luck!