Okey now i tested the windows 7 x64 and i would say 4.5/5, most works right except some dialogs (for example creating a new project) begins as a black screen and slowly paints itself.
fortunately jdk 11 downloaded from the b4j page works with UI app and the packager works, but the packaged file does not lol
so far i am impressed that we are able to run wpf projects in linux and the jdk too, this was impossible 2 years ago.