"More a rewrite instead of a migration"...
Translation: It sucks right now but the good news is... it still slurps!... So this lets M$ into the Linux prom (stops them being booted out of non-M$-platform events anyway), and gives them bragging rights & marketing creep... Is that a fair assessment?
....."If you have a 10-year-old application that your company relies on, we don't recommend attempting to port it to ASP.NET Core... The problem is the amount of porting work needed to work around missing APIs and Windows dependencies."
...."Note that the ASP.NET Web Forms framework is not implemented, but only the more recent ASP.NET MVC and Web API. Even if your application is already ASP.NET MVC, porting will be more "a rewrite instead of a migration,"
....."There are caveats. Only a subset of the .NET Framework is included, essentially for console or web applications."
....."The tooling both for Visual Studio and the command line is still in preview, with full release expected with version 1.1 of .NET Core towards the end of 2016. Visual Basic is not supported for ASP.NET Core, and the SignalR real-time communication framework is not yet done."
...."In some scenarios though, you can only use .NET Core. This includes the forthcoming Windows Server 2016 Nano Server, a cut-down server designed for cloud deployments and microservices."
...."This is good work, but areas of confusion along with porting challenges will slow its adoption."
...."The first time you run the command-line tools, Microsoft warns that it is collecting telemetry... No personal data or code is collected though, according to".... ???