I've been listening to some shaman interviews and getting a sense of what is understood by shamanism these days. It's interesting. The two obvious categories are traditional ethnic community shamanism (where it exists?) and modern 'neo-shamanism' which is blended with new modalities like family constellations or other healing methods, kabbalah, castenada-ism, psychedelics--whatever works, or someone can put together as a marketable package.
These certainly produce strong experiences, shift from superficial values and ways of perceiving, and the better versions demand training and commitment from people. It reflects a hunger for ways to develop and channel emotion in an emotionally confused world. Even the Healing aspect is emotional need, though where there are results, power enters.
However, while theoretical structures taken from some native schema have consistency and context, the creation of a blend of theory with bits and pieces on non-traditional principles sacrifices the abstract clarity of Principle, and therefore of Power. I simply cannot detect much power in most of the earnest sages I have listened to, though I know that shamanic trance methods etc are powerful experiences, and are understandably craved in our bland homogenised world. Experiences are not the same as power though. Power is in being.