Context: I have used Elastic Beanstalk in real production apps for years. For my Rails side project, figured I would use Beanstalk instead of Heroku so that I'm using the same platform (although I have also used Heroku in prod settings).
Quick summary is the AWS tutorial for launching their Rails sample app in Elastic Beanstalk doesn't work at all. I though maybe my Rails install was borked somehow, so I tried launching a sample app at Heroku. Worked on the first try.
Heroku really spends time making sure everything works out of the box, and that's what you're paying for.
And the next time I do it, it's like it's all brand new. It never gets easier.
Also it's very early stages - but the goal would to be better than Beanstalk