In my brief try-out of it, it felt to me like if you want to do anything different (e.g. your own implementation of something), you pretty much need to switch to Scala. It's a Scala framework first and foremost.

A minor demerit was getting SBT and Play Java to work correctly in IDEA was enough of a pain to make me wonder how much overhead that was going to incur in the long run.

If someone who has used Play Java in production on a large project can weigh in on whether these points are true or not in real production use, I'd love to hear it.