I'm surprised at the lack of love for Groovy. Groovy rocks... I made the decision to switch all of our development to Groovy (and Grails) a couple of years ago, and I haven't regretted the move at all... it's gone astonishingly well. Much faster development than in raw Java, but without a huge learning curve, and yet still with seamless integration with existing Java libraries, plus more than a few very cool native Groovy libraries. What's not to like?
I've been using and following Groovy for varying degrees almost since the first release... I'm not sure what you're getting at. As far as I can tell, the only real, persistent, commonly-cited flaw with Groovy has been performance. And that is a fair criticism, but - at least for what I'm working on - not a "deal breaker". And I'm still optimistic that the Groovy team will eventually be able to follow in the footsteps of the JRuby guys and do some big things to take advantage of method handles and invokedynamic to speed things up. But even if they don't, Groovy is fast enough, even if it's not exactly setting the world on fire.
If there are any other serious complaints about Groovy, I haven't heard them, and/or haven't encountered them myself.
