For me, Groovy always have this feeling that's quite the opposite of Scala: it seems that it was a language that wasn't very thoroughly
implemented and has all of these bolt-on stuff on top of it. Scala seems more solid to me because of the academic background (to think that a type system can be turing complete..), and it seems that Clojure found a place on its own.
In general terms, one of the flaws for me is that I can't quite decide what's the direction that Groovy's going. For example, the 2.0v is introducion static features, but AFAIK I never noticed any interest on static features (of course the groovy team should have much more to say on this). Other thing that I didn't like was the stack traces when an exception ocurred: due to the nature of the MOP, the stack traces were always very full of 'garbage' (this was some time ago, I don't know what's the story now). Another example is on the link: if you want to enable invokedynamic, you have to switch some flag on the compiler. If you compare to jRuby (which I know is not directly comparable but as an end user I really don't care) it's alread turned on if you are using the proper jRuby and JDK versions.
OTOH, I think Groovy nailed the Java interop spot on (flawless Java invocation/interop, integration with Ant, maven, etc) which is probably one of the good reasons to use Groovy.
If you consider SO to give a reasonable feedback on popularity, here's the nr of tagged questions:
* scala 549
* jruby 342
* groovy 599
* clojure 120
* ruby (for comparison) 7,115
Having this said, I still think that Grails is one of the best web frameworks for the JVM, although I would like it more if the plugins would have better maintenance by the community.
In general terms, one of the flaws for me is that I can't quite decide what's the direction that Groovy's going. For example, the 2.0v is introducion static features, but AFAIK I never noticed any interest on static features (of course the groovy team should have much more to say on this). Other thing that I didn't like was the stack traces when an exception ocurred: due to the nature of the MOP, the stack traces were always very full of 'garbage' (this was some time ago, I don't know what's the story now). Another example is on the link: if you want to enable invokedynamic, you have to switch some flag on the compiler. If you compare to jRuby (which I know is not directly comparable but as an end user I really don't care) it's alread turned on if you are using the proper jRuby and JDK versions.
OTOH, I think Groovy nailed the Java interop spot on (flawless Java invocation/interop, integration with Ant, maven, etc) which is probably one of the good reasons to use Groovy.
If you consider SO to give a reasonable feedback on popularity, here's the nr of tagged questions:
Having this said, I still think that Grails is one of the best web frameworks for the JVM, although I would like it more if the plugins would have better maintenance by the community.