Physically addictive? No. Psychologically, yes. I like LIP's term "habit-forming" real well.

It doesn't matter what the substance is, in the hands of some people with compulsive or addictive tendencies, they're going to form some sort of dependence on it even if it's not classic physical, craving-driven addiction.

Same thing with some people and cannabis being a gateway drug no matter what the studies say about that. For some people, it is a gateway drug. Not because cannabis is some sinister introductory substance that compels people on to more serious drugs. But because certain people are wired so they're destined to go through the gates to other drugs no matter what they start with. They could start with chocolate ice cream and that'd be a gateway substance.