To list a few, right when the whole debacle regarding concurrency started, they had a bug with their scheduler which wouldn't terminate processes. What ended up happening was that customers got billed for processing time they didn't use. Heroku fixed the billing issue after they were told of this issue. There was also a minor security issue where you could grant applications access to heroku via oauth, but you couldn't reject it. Not a huge deal, but it would be nice to revoke apps instead of leaving them out in the limbo. I could probably name off a few more issues I've been having with Heroku, but my point is, I'd rather they spend more time fixing the current issues instead of spinning off new features.