I played around with the JME2/3 engines, JME2 was awesome, JME3 had a lot of really cool features however pretty much forced you to use their netbeans based
IDE to develop, which though cool, is netbeans with a restrictive bulkey UI, which just doesn't blend in anywhere on any platform and I was never fond of it. So I personally dropped JME and started toying with LWJGL and JOGL. Their more stable, and have much better documentation as well as implementations which you can view the source code to. JME is working on improving its documentation it looks like, however its just taking way too long imho.