I'm also curious if any large projects use it. We tried it out for a couple weeks - it worked fine but we felt overly constrained by the configuration rules and ended up rolling our own solution.
We use it at Mi9 to run some of Australia's highest trafficked websites, like ninemsn.com.au (and family of new sites) and jumpin.com.au. Also Stan.com.au (Australian Netflix competitor) runs their micro service architecture on Elasticbeanstalk