Well,
What i have been observing and seeing is that people truly deviate when they start following a particular sufi school of thought. For example there is a new found school of mysticism namely the silsila-e-azemia. Although they pretend to be very sincere and islamic but most of their practices and rituals are not really very islamic.
Many of my close relatives are in this school and they have told that the most important worship, according to Mr. Shamsudin Azeemi, is meditation. this is so important that it even surpases the importance of Salah. Also, several kinds of meditations are propagated which attract people of all sort and especially girls because they claim to provide a meditation which brings the heavenly beauty in a girl.
Second this is their constant elevation of spiritual powers which are considered by them to be the fundamental purpose of life. They claim that the purpose of human being on this earth is to activate spiritual powers and use them for the benefit of mankind. However, without a proper noursihment of naffs and character, it si virtually impossible that such powers would be used for any benefit of mankind.
Further this claim itself is completely in contradiction to Quran. Quran dislikes seclusion and orders to spend life being a human among human beings. ANy kind of sorcery or magical powers are not the purpose of life.
According to ALmighty, the purpose of life is to serve God and live our life by keeping ourselves within the laws of nature & God. Prophet never taught anyone such powers and never instructed in a single saying to acquire such powers. All stress is given to the proper noursihment of moral character and to be obedient to ALmighty. If, in any case, there are any powers, Almighty himself choses and gives them to the chosen for a set purpose and for a certain time period. This is called karamat or maujzah (Miracle).
To conclude, present day sufism is misguiding the masses and taking us away from the real teachings of Quran and recongnized Sunnah.
For every muslim, the first duty and very basic purpose of establishing salah five times a day should be to read and understand Quran more and more. As much we would understand Quran, as much we would come to know about the guidance of God in relation to all matters of life, including Sufism.