I am just really looking forward to the lambda support. I don't care how it's implemented (generated anonymous inner classes or whatnot) or if the syntax isn't exactly what everyone might have wanted... I just want some simple block support. I am just not thrilled about Scala, so I won't even go there. I worked on a large Swing application a few years ago (two years of development work) and how I would have loved it[lambda]. I would have saved thousands of lines of boilerplate (due to listeners and such). We had used Groovy in parts of the application but that almost killed the product as it was just too slow for the UI.
Edit: Go here to get the binaries directly http://jdk8.java.net/download.html