I've done a medium sized spring project last year, and found the language quite good, but the framework itself and the general ecosystem really too cumbersome.
The only framework which I can recommend, is Dropwizard (http://dropwizard.codahale.com/), which tries not to be a framework, just a glue between some really nice libraries and tools.
I'll start with "raw" java next time i'll want to try playing with rest services.
If it isn't what you're looking for, I'd be curious to hear which of these qualifications it fails at.
Our product is a browser based web development tool that comes with its own middleware/framework with a UI built just for it. I think this approach while not as generic is superior because you get the benefit of real tooling not just a generic framework that you need to manually glue together.
Spring like many frameworks are designed to be generic and pluggable into other tools/IDEs, unfortunately once they become complex their benefit is greatly reduced for most projects.
Support us so we can continue to improve on the product, visual UI building and integration is on the horizon :)
For? If you are developing REST applications, the JAX-RS standard is great, lightweight, and mature. I have used both Jersey and RestEasy without any problems.