I had mine done about five months ago (vertical, 12ga), and I'd say it was my easiest piercing to date. The pain was intense, but over in a snap. Walking home was absolutely fine, and it healed faster and easier than any other. However, no other piercing has *ever* made me involuntarily twitch, even though I was relaxed and actually concentrationg on keeping still. Two friends of mine have the same piercing, same guage, and both say their experiences were really similar- intense pain, the whole body twitch thing, but over and done with just like that. Totally worth it, IMO.
YMMV, of course.