My experience has always been good. I think anyone could benefit from seeing a therapist even without mental illness.

What they ask really depends on why you are going. Like are you going in for an assessment at a clinic to maybe get a diagnosis? In that case they would ask all the symptoms you are having. How long have you had these symptoms. Do you have a family history of others in the family with mental illness. Your own personal history with your own family. Have you had problems with drugs and alcohol. Things like that.

If you are going to get help in general or for a specific issue the first question will probably be what is it you want to get out of therapy? Why did you come in the first place? Some are better than others. Some will push harder than others. It takes awhile to build trust and get to know each other. A good therapist will take some time to build trust and figure out the best approach to take with you. The same therapist may take a different approach with me. In my experience they are people who really want to help others and that is why they do it. There are bad ones though. If you get a bad one find another one you click with.