Will be using a wood fired arch for the first time this season, so this isn't firsthand, but here's what I've absorbed...

Like Russell said, wood is more labor intensive, even if it's free. I don't mind the work, and I figure I have all year to find and collect wood.

Wood takes time to start up and shut down. If you needed to shut down in a hurry, with oil you just flip a switch. Wood... unless that switch is hooked to a sprinkler system in the firebox, no dice.

I can't speak to the straight cost of wood v. oil (but there a many here who can), I still have a quote stuck in my head from my association meeting this past weekend... "Wood? If you're going to chop wood, fine. Then sell it and buy oil!"

I might go to oil as I expand, but for now it's wood. Check out some of the older post I linked below. Lots of good info there.

buying wood vs. buying fuel oil
Converting wood to oil
how many cords of wood has everyone gone through
wood fire/oil fire
Wood? Oil? Propane?