Does anyone here have personal experience with Reiki?
I've read a little about it, but I don't quite understand it.
Does it actually work in a physical sense or are the effects more spiritual and mental?
Well, you mentioned a very sensitive topic. I try my best to write an answer which makes some sense, but in the meantime, I do not intend to hurt anyone's personal beliefs, religion or anything else.
I have personal experiences, but they show something else than that you can hear from the "Reiki Masters."
A few years ago, I was really into many kinds of New Age and spiritual thingies, Reiki included. Since then, I have understood: okay, there are things which do work, no matter if you believe in them or not... but this does not mean that one should believe everything that can be read on "spiritual" things.
In my experience, the so-called Reiki thing is nothing special or mystical.
It indeed can happen: if you are open enough (psychically meant), then you can "load up" others with energy, or help them easing some pains, but... that's all. Sometimes when I am in an extremely positive state of mind, I can feel some warmth in my hands, but this is neither mystical nor oh-so-spiritual.
You see, my reasons for becoming sceptic about Reiki was the behaviour of certain "Reiki masters". (I will not mention names.) They said many beautiful and idealistic things about spirituality, healing and universal love, but their attitude was rather different from that. Even if they preached that practising Reiki will lead you to a more open, spiritual and loving state of mind... some of them showed a big amount of bigotry, and these "initiation degrees" and "spiritual symbols" caused many unhealthy "competiting" behaviour in the communities. Not to mention what a bombastic business it was for them... this attitude, in my opinion, is very far from the true spirituality and healing they always spoke about.
So, you asked a very good question.
The thing may work to a certain level, but it is better not to take it too seriously. For most of us, it is very simple: if you are in a honestly good mental state, you become physically healthier, and therefore you will have a more positive atmosphere around you, and touching someone will make them feel better. That' s it. Nothing magical or special.
I would rather not start to discuss the question of prophets and saints, because that is very different from training consciously and intentionally to become, well, "spiritually more developed".
I honestly hope I managed to not write anything that would hurt anyone's feelings.