The ease of use and how it can easily integrate into other platforms such as Adobe Flash or HTML5. It also has great support from third party developers who have created applications using its API's. I dislike that there are not more options in terms of codecs supported by WSE. There should be better codec support than H264/AAC only. We needed an easy way to broadcast webcams to multiple devices including mobile phones which was previously difficult to do without having to rely on expensive hardware like XSplit Broadcaster Pro.