Still a little odd for a release announcement. It feels disingenuous to only afterwards make the fine-grained distinction that yes the libraries are technically v1, but the tooling is still in preview.
Kinda like announcing your new line of cars is ready for purchase today! Except that down in the fine print you might find out that the engine is ready to go, but the steering wheel, headlights, dashboard, and pedals are all still in development and so it's justifiable that they're broken.
Was like that also in the previous release.
The .net core was rc2 and the .net core sdk was preview1.
I use it, and i think it's ok.
The sdk it's just a build system. the real value is the .NET Core, that mean the coreclr (the virtual machine) and the foundation libraries (corefx).
I can change the build system one month from now, to build a project using the old packages.
It's not a car (engine vs wheel).
It's more like food vs marketplace. the food it's the real deal, the markeplace may be incomplete (no parking).