I don't think you can say "fairly common." Cannabis is not associated with the physiological consequences of addiction, much like alcohol, hypnotics, stimulants, and opioids. There are risks to using cannabis, and one can develop behavioral/psychological dependence on the substance. It is not clear what all of these risks are, and we need more research to understand them better. We also need more research in the benefits of cannabis, including it's use for chronic pain, and post-traumatic stress disorder.