I use a cast iron skillet occasionally for a Pizza Hut-style pan pizza (much better than PH, of course). It works really well to get that oily fried bottom that a good pan pizza has.
Currently, I use a heavy-duty pizza stone (California Pizza Stones), which does a fantastic job. I'd imagine a cast iron pizza pan would work much as a pizza steel works, so it should be fine. I'd most likely use it as a steel/stone and leave it in the oven, heat it with the oven, then toss my pizza on it, as opposed to putting my pizza on it first, then putting it in the oven from room temp.