I have some experience of the charismatic movement from my Evangelical background.
My personal opinion is that almost all of the modern charismatic and Pentecostal movement is built on spiritual and psychological deception, both witting and unwitting. This is not to condemn all those devout souls who are looking for a greater and richer experience of God. But in my experience and my knowledge of many of the streams of charismatic activity it is not of God, not least because it is almost entirely anti-Traditional, anti-Sacramental and anti-Ecclesial.
The greatest danger, as far as my experience goes, is that 'spiritual power' is divorced from holiness of life and becomes something exciting to seek and use. There is no spiritual power apart from life in the Church, and the true Church is the Orthodox Church. In all other places there may be truly echoes of life and real experiences of God, but if the teaching of a Church is leading away from the Apostolic Faith then it is not of God, and all of my experience of the charismatic and Pentecostal movement is that it leads people away from Apostolic Christianity.
I have seen terrible spiritual manifestations that in any other historical context would be immediately described as demon-possession but in many charismatic groups are lauded as being signs of the presence of the Holy Spirit.
Yet, there is a true experience of the grace of the Holy Spirit which can be found in the Orthodox Church. There are miracles and healings, even those raised from the dead. There are prophecies and words of knowledge. There are monks who cover their eyes and hands because they shine with a divine light. There are icons which give forth oil. There are apparations of the blessed Virgin Mary. Orthodoxy is replete with miracles even in modern times. But these are not for all and they are not signs of having begun the journey. They are manifestations of the presence of the Holy Spirit in hearts and souls which have been transformed to a great extent by years of attention to that same Holy Spirit.
Indeed Orthodox Christianity is entirely Pentecostal. The aim of the Christian life is the acquisition of the Holy Spirit. But the Holy Spirit manifests himself especially in the development of a holy life. This is rather boring I suppose. And is a long-term project that requires commitment on a daily basis to the ascetic way of prayer, fasting and service. It is not popular among most charismatics because it is not glamorous and it is not immediate.
These are only my personal opinions, although they are based on real experience. As far as I can see Orthodoxy, both EO and OO, repudiates modern charismatic and Pentecostal experience as deception, even if it is a self-delusion. In some cases it seems to me to be clearly demonic. But to repudiate the activities of such groups is not to diminish the true experience of the Holy Spirit which we believe is offered to all those who become members of the Apostolic Church. My own very weak experience of the power of the Holy Spirit is so much greater within Orthodoxy, and is especially acute since I have become a priest. Everything must be done in the power of the Holy Spirit. We are truly Pentecostal people.
I do not believe, from my own experience, that most charismatics and Pentecostals, are being taught truth and are being led into light and life. Quite the opposite I am afraid. I do not believe that the protestant version of Pentecost has any place within Orthodoxy.