Things I've noticed: * Segmentation Fault when deploying a Rails app, Heroku just works. * Ability to add Postgres but no ability to add Redis in the same ecosystem, you have to step out of the app platform, Heroku just one click and you have Redis associated with your app and many other add-ons.
There is a lot of potential on Digital Ocean, it in its infancy, the thing I like the most about it is $ for spec, with a $50 Heroku dyno I get 1GB RAM at DO the specs are way superior.
The blogpost mentions CLI usage and the global naming issues, those are annoying sure, but not the breaking point for Heroku.
The biggest competitor to Heroku IMO it's themselves. The fact their price remain the same even though specs and computational power has became way cheaper.
I would happily keep stuff in Heroku if they revisited their pricing policy.