.NET Core brings so many changes, even if you don’t write production code on a daily basis you might want to have a refresh 
and that’s what I did with Christian Nagel’s book.
It is very well flowing and never too near a knowledge base article – Christian writes very well. The content in there is for Visual Studio 2015, but you can definitely use it with 2017 as well.
I was particularly interested in the .NET Core and ASP.NET Core sections, and I reckon they are really a fresh and clear starting point on the matter. Given we are talking about a printed book it might not be fully updated, but again it is a matter of a few touches here and there. It is worth remembering that it is stuff in continuous evolution, so I would expect it.
But the book definitely isn’t just about .NET Core and ASP.NET Core. It covers extremely well the stack from top to bottom, and I quite enjoyed the What’s new in C# 6.0 section and the recap from C# 1.0 to 6.0 in the first pages. As I said it is about the whole stack, so once you are off the first 450 pages (Part I is all about the language) you can tackle the IDE, the Compiler Platform and more.
I particularly liked how broad the approach was. The Testing section for example mentions not only MSTest but also xUnit, and in both .NET Core and .NET Framework, the Diagnostics section mentions Application Insights, etc. Christian did an amazing job summarising these broad but also specialist topics, and the result is really well-integrated
I am a huge fan of books, and I really enjoy having a well-written reference I can dive into instead of going straight to Google, losing context in the meantime. This is one of these, and I also strongly suggest this book to whoever needs a refresh or is tackling C# and the Microsoft stack with a bit of past experience.