The CPC at Bing is certainly lower than in Google's AdWords, but I noticed that when you run location -based campaigns Google delivers much better conversion rate. I decided to investigate and (based on analyzing the use of location context in the results) realized that location granularity is much better at Google than at Bing. It looks like Bing always delivers search results for "macro location", while Google sorts results considering your exact location. As a result, your location-based ads appear in locations where they are not that relevant. When people click on them, they are less likely to use your services as you are far away, so you're wasting money on these clicks. For example, if your client is in Brooklyn and he is searching for "oral surgeon", he gets results (incl. paid ads) for Manhattan and Queens [this is just a hypothetical example]. My recommendation here is to always specify location within the search term (i.e. "oral surgeon Brooklyn") in your paid ads at Bing and not to rely on their location based algorithms.
The CPC is better on Bing/Yahoo and they have 30% of marketing share. I use Bing 90% of time and adwords 10% of time because of this.
Where did you get this number (30%)? As far as I know it is only about 6% worldwide - you can see real time statistics here: http://marketshare.hitslink.com/search-engine-market-share.aspx?qprid=4&qpcustomd=0&qptimeframe=M In US the number is 18% (at the end of 2013), see this post: http://searchengineland.com/bing-ends-2013-with-all-time-high-in-us-market-share-but-google-also-up-comscore-181876
Bing is cheap but to this day we are top for tons of keywords and not 1 single click yet, so I would say it is slower than google but cheaper for that reason
The thing I don't like about Bing Ads is when you first start your campaign the software may start your quality score at like 8/10. You think, oh, great, I am going to refine my campaign even more and drive all this damn cheap traffic to my site. However, as the time goes by, your score may drop to like 3/10. I don't understand why they mislead their customers that way. It would be nice if their software was a bit more proactive when it comes to estimating a quality score. Sometimes it takes a week before you see that drop.