I have never tried either, I have not run the PPC ads (tho I may use a voucher I got too.) Google is a bit expensive for certain keywords and I am wondering in Bing would be a bit more reasonably priced for you? They are gaining in popularity, I know people who prefer Bing for the searches - tho I am still a Google girl.
I am curious to see what everybody says here as I have been playing with the idea of PPC for one of my blogs.