What is a Ketamine infusion like? Side effects? Benefits?

I'm going into the hospital for a five day Ketamine infusion for pain and headaches. At first I was excited because it is a new treatment that doesn't cause any painful long term side effects. Now I'm scared because I hear you get hallucinations, Out of body experiences, panic attacks and become disassociated from reality and self. Is this true? What has been your experience? Did you benefit from this treatment?