RyuJIT FAQ is on the .NET Blog
Go forth and read it to see if it answers your questions: http://blogs.msdn.com/b/dotnet/archive/2013/11/18/ryujit-net-jit-compiler-ctp1-faq.aspx
One thing that's buried in the FAQ: we fixed bugs that people reported, so if you uninstall RyuJIT CTP1, re-download it and reinstall it, you'll get an ever so slightly less buggy version!
If the FAQ doesn't answer your questions, I'll answer other questions over here. Fewer people read this one, so I'll get myself into less trouble than my previous Answers to Questions :-)