Tarot cards are simply a tool, or a focal point, and its the interpretation of the images, their placement, whether they're positively or negatively aspected, etc that helps the reader tune in to the subject. I used to read and still have both of my decks, but I eventually got to a point where I no longer needed the cards as a focal point... and tarot isn't really that useful to one who walks the path of shaman, anyway.
Is it magic or mystical? That depends on how you define those terms. It does have a lot to do with intuition and in some cases, probably psychic ability to some degree. I've seen many very specific readings done for people that the reader did not know and had never seen before. Likewise, I've met psychics who I'd never met before that told me specific details of events in my life that no one knew but me. So yes, I believe some people are gifted in those areas.
Of course, I've also seen many roadside "psychic/palm reader/tarot reader/crystal ball scryer" types who are only there to feed you a line of bull and take your money. For me, here's the key to knowing a fraud... if they can tell you things about yourself or your life that you and only you could know, without any input from you, they're probably not a fake.