Done well and content marketing is massively, massively successful. Done with good intentions but not enough resource (time and money) and you'll experience little, if any, positive return.

In summary you need to be pouring out quality, mapped content that resonates very, very precisely to your buyers persona. I.e. make sure you have content that addresses your prospects primary issues and then show them how you can make the problem go away. Then setup your workflows to nurture the conversation and your buyers awareness and education. Never sell only ever inform. Let your prospect choose to buy.