Jersey is extremely simple to get running, even on App Engine (if you're into that). Getting Flask, uwsgi, and nginx running on OpenShift isn't particularly difficult, but I had to follow a detailed blog post to get it working.
And, personally, the problems don't end there--I think I'd quit programming before going back to any Java-based hat-on-top-of-JDBC. Scala's Anorm/Slick have given me enough of the "there's a better way" to make going back really unpalatable.
For what it's worth, Akka is even more relevant to what I'm doing.
Play, for me, gives me good tools for doing stuff, and I can make individual services as big or as small as I want.