I have seen it demonstrated in a professional setting by a trained psychologist and my clinical supervisor was a trained hypnotherapist. His opinion was that it could start a change process by addressing any subconscious resistance, but the client still needed to take action to maintain any progress. In his experience, he wasn't seeing enough long term benefits with enough of his clients to make it a calling card for new referrals as he had a broad range of skills and experience. He did still use it, but only in specific cases and the clients needed to demonstrate a certain level of motivation and commitment. Mainly things like smoking cessation and weight loss or to eliminate bad habits; less so for serious mental/emotional issues.