Substance is a free (BSD) look and feel and comes with many skins and configuration options.
It is easy to install and configure. I used substance even for NetBeans in the past.
NEW 2016: Java EE 7 Workshops: Bootstrap, Effective, Architectures, April, 4th-6th, Munich's Airport
On demand workshops: Java EE 7 Bootstrap, Effective Java EE 7 and NEW: Java EE 7 Testing are available for streaming
A book about rethinking Java EE Patterns