I tried openshift a few months ago for Rails. A real pain in the butt. They dont have simple deploy like Heroku. Even heroku can be time consuming in the beginning to get right, openshift was even more complicated. It may work better for Java I don't know, looks like they are right on the bleeding edge with support for Ruby 1.8.7.
Our roadmap has more support for newer versions of Ruby coming soon. We started with the base packages in RHEL but are now working to also bring newer versions as standard cartridges. That said, you can also use a DIY cartridge to get Ruby 1.9.x
Thank you for posting your experience trying it with rails, I agree deployment of a non-trivial app to heroku can be a pain the first time but once you get everything working its a breeze for subsequent deployments.
