I started looking at play 2.0 for the first time today. I got a few hours with it at least, and I've been impressed with a few things.
The first and biggest thing is perhaps the most simple: compile on the fly. Grails does this, but very badly, and if I'm observing right, I think I can see why. It seems that Play compile checks at request time, not at file save time. As one who grew up computing, Ctrl-S or it's equivalent has become a nervous tick. Grails recompiling at save time almost always just ends up trashing the environment as I save about ten times a minute, and I end up having to restart it, which is very slow.
With FSC, Play compiles changes very quickly and I barely notice a lag at all. It doesn't get stuck anywhere I've noticed yet either like Grails can.
I feel like within a couple of hours, I got pretty far into having a functional, albeit basic web app going. Working with Anorm is interesting too, I'm not sure if I like how they've done it yet, but after years living with JPA and Hibernate's arcane query structures and unexpected query stupidity (although there was always a good reason, it was still annoying), I find this way of integrating SQL and code better than most. It has some similarity with O/R Broker which is what I've been using with Jersey so far, but Anorm is more sophisticated and I think easier to work with.
The error reporting in Play is also excellent. You can see quickly and precisely what went wrong with your code, there's no guesswork and decrypting enigmatic error messages, it just tells you with your source code right there: this is where it's broken!