When comparing Play 2 vs Ninja, the Slant community recommends Play 2 for most people. In the question“What are the best Java MVC frameworks?” Play 2 is ranked 3rd while Ninja is ranked 5th.
Ranked in these QuestionsQuestion Ranking
Pro Very fast and easy to install, it is a revolutionary framework
Pro Great resources
With some basic starting tutorials and a fleshed out documentation, there will be no need to go asking others for help, there should be enough for a developer to find a solution.
Pro Asynchronous requests
Everything with Play has been built with asynchronous requests in mind. This will result in the application not blocking results while waiting on other operations. With this implemented your application can be developed with multiple threads in mind without worrying about hanging on one request before it completes another.
Pro Rapid application development
All error checking and testing done in the browser only needs a page refresh to show the latest updates. This is huge, allowing the ability to code in real-time and make quick edits. Without it the develop would need to reboot/recompile the entire application to test with new data.
Pro Supports Scala
Pro Simple set up
Once dependencies like maven are installed it is up and running in minutes with one simple command.
Pro Easy horizontal scaling
Ninja is stateless by design. This makes horizontal scaling very easy and just a matter of adding servers.
Con Not backword-compatible
Applications that have been written in Play 1 will not be supported in Play 2 as the core of the framework was rewritten in Scala. This includes plugins that were working in Play 1 as well.
Con Becoming a Scala framework
As Play continues to develop and mature it seems as if it is becoming less of a Java framework as the core has been rebuilt in Scala. This may deter adopters.
Con Steep learning curve
Con Little user choice in organization
Since most of the code and folder structure are automatically generated, this leaves little room to the developer on how they will organize their project.