> How does this support windows platform developers?
Current Windows developers? Well, even though the primary target is the iOS developer who wants to try out the Windows platform and Store, it definitely could help existing Windows developers.
How? Simple. If you are a Windows developer, you may well have been asked to create a Windows version of an iOS app, because many apps start their lives on iOS.
Wouldn't it be nice if there was a tool to take Xcode projects and make them into Visual Studio solutions? Then you could take the code and work on it in the tools you know and love.
> Should you learn iOS
There isn't much to gain if you currently write Windows apps and want to continue writing Windows apps. Writing Windows apps from scratch in a Windows development environment is always, always, always going to be better experience.