Here is my personal view of Reiki from my experience.
Reiki is experienced differently by different people and given differently by each practitioner. I think of it as a two-person meditation. The practitioner guides the meditation onto the client with hovering, or light hand placements, on the client, from head-to-toe.
As the practitioner, I "receive" the meditation as well.
In my experience, some people say they feel absolutely nothing, while others have told me they no longer have a migraine or other pains. It can do no harm, and "it's" okay if they "don't" feel anything.
Because of this, I do not ever say I will heal someone or call myself a healer. I tell people they "don't" have to believe in anything; they just need to want to feel better. I believe any form of stress reduction and relaxation can be healing and beneficial to both the giver and receiver.