It's great news that the Netbeans team has announced the release of Netbeans 6.5! Even better news for the Groovy and Grails (and Griffon) community that there is now a major open-source IDE with Groovy support. Although an Intellij groupie myself, I used netbeans in the old days when it was Forte and I've watched as it has made major leaps and bounds in terms of speed, usability, and a functionality. I've also used Netbeans (and Forte for that matter) for J2ME development because at a time it was the best IDE out there for that sort of thing, integrating seamlessly with Sun's J2ME toolkit. I can't speak to whether or not that is still true having not done any of that sort of development for years. I always preferred Netbeans to Eclipse because I like how everything in Netbeans feels like it fits together. I've always felt Eclipse felt a bit like the Frankenstein Monster of Java IDEs as the different plug-ins and such don't look, feel, or work the same.
Just a few weeks back when it had come out with it's last milestone release, I used Netbeans 6.5 it at a client site to train them in the development of a Grails application that I had been working on for them. Just three of us were able to get it configured (along with Grails, Groovy, and Java) on all the classroom's systems in no time (well maybe an hour or so). I only had the chance to play with it for a few hours but it seemed completely useable with code highlighting, error checking, code completion and running Grails applications in the IDE itself. I would also say that the overall look and feel of Netbeans and it's responsiveness were highly improved over older versions. Older versions always felt clunky to me.
Netbeans won't be replacing Intellij for me anytime soon but I'm always glad to see competition in the marketplace and more choices for my clients.