Ranked in these QuestionsQuestion Ranking
Pro High level - focus on what you want to do rather than the plumbing
Similar to Vaadin & Meteor but in Scala.
Pro clean modern design
This framework is much more modern than a lot of its competition (e.g. Spring MVC).
Pro Components similar to desktop GUI framework for high level & fast construction of complex GUIs
Pro do it all in Scala in a type safe way
Con Very new and hence doesn't have a big community yet
Con Limited documentation, no books or 3rd party tutorials/samples
You'll have to be willing to be a pioneer.