I think there is a huge need for these kind of frameworks. They combine the convention over configuration productivity and tooling that rails and its clones provide, while letting users tap into the massive java ecosystem. Others like this include dropwizard and spring boot, but there's always room for more.
Java ain't perfect, but a lot of hard problems have been solved for the ecosystem and building on top of those solutions will save teams time and money.
Java's enterprise system has actually trended towards the convention-over-configuration of RoR since it was heavily revamped as JavaEE 5 (and obviously renamed). JavaEE today is heavily dependent on meta-programming and containers like TomEE and JBoss can be built in minimal configurations.
I think Jodd is interesting in the same way NodeJS is interesting. If you're more comfortable building your framework from the ground up, you end up adding only those pieces you require. If you're happier having an entire application server at your beck-and-call, start with a full application server and (if necessary) remove what you don't need.
Me too. What I like about Clojure (and other JVM languages) is that I can choose how much I want to take part in the JVM ecosystem. There is usually a spectrum from pure-clojure <---> clojure-wrapping-java <--> pure java and I get to choose where on that spectrum I want to or need to be based on the needs of my project.
Since the Java ecosystem is huge, this gives me a lot of confidence that most of my needs will be met by existing tools.
I haven't done much with the other JVM languages except play around with them (did work with a small jython project about 10 years ago...). Have you encountered any impedance mismatch? Or weird cross language bugs?
Java ain't perfect, but a lot of hard problems have been solved for the ecosystem and building on top of those solutions will save teams time and money.