I dont use netbeans so cant comment on that one but java5 has some new features over java2:
> there is now a printf method just like the printf function in C (surely it should be called printm!!!, oh well..)
> Better way of dealing with enumerated types
> The abiliyt to pass varying numbers of arguments to a single method without having to overload it.
I'm sure there are a few other improvements too, but those are all i have heard of so far, but i havent done any java5 coding yet