There is something called "Richardson maturity model", which pretty clearly specifies different levels of "restfulness": http://martinfowler.com/articles/richardsonMaturityModel.htm...
I do agree that this model is a good set of steps to build better APIs but then, how do you call them? RESTful Level 1 API?
My point with this article is just to call API what they are (usually just HTTP APIs). I'm totally against the use of the REST buzzword these days since it doesn't mean much anymore: everyone has a different view on it.