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.
Jersey is very simple to get running, but it has pretty big drawbacks: there's not much you can do with it. Dropwizard and similar ameliorate this a bit, but compared to Play (which does have onboarding challenges) you have a long road to hoe to go from Jersey to a nontrivial app.
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 the last few years my apps have trending towards components that don't do much individually, but can be made to work well together. I haven't used Jersey on anything major, but it fits the profile I'm looking for.
For what it's worth, Akka is even more relevant to what I'm doing.
That's fair, but Jersey's not really very good at many of those individual things. It's not a great tool for a JSON API unless your consumption target is pretty much the same domain library on the other side because you'll end up neck-deep in @JsonProperty. It's not great as a frontend because Freemarker, StringTemplate, and Velocity are all pretty gross.
Play, for me, gives me good tools for doing stuff, and I can make individual services as big or as small as I want.
Welcome but the guy who invented it, Per Wendel and those who help him maintain it are the ones who deserve the credit. If you're into Lambda's (I'm not yet but trying to bend my mind to want to use them), he's working on adding them for version 2 which should make it even simpler.
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.