I'm not a fan. I currently have an iPhone paid for by my employer because I'm in rotation for 24/7 tech support. It's great that I can save on personal mobile bills, but at the cost of giving my employer the right to monitor my voice calls, SMS messages, etc if they have "reason" to. I doubt they would under normal circumstances, but they make it clear that they could. Also, I don't like the idea that work-related software could mess up my device. And I don't like the idea of handing over my device to the IT folks at work when I have personal information on the device. Also, mixing both personal and business contacts can be a recipe for disaster, should you get some kind of malicious software or virus.