Running PHP on a windows server-your views

HI all. I would like some honest answers and if you have any experience with problems or no problems running PHP on a windows server. Basically we are interested to know if there are any problems/security issues/stability issues/performance issues or any other issues running a production site (big live site) on a windows server. Im assuming it will be running IIS. The site is very important and any issues will hamper the functionality and accessibility of the site. All your responses will be greatly appreciated. TIA Angelo --