One person wrote :

He was the manifestation of satan, the devil and antichrist, the trickster and evil whisperer, the Golden Calf, Beelzebub, Lucifer, ahriman, Mephistophles and Iblis in the flesh (ل), hence why long ago I dubbed him Baha'u-Shaytan. His objective was to carve a legacy for his ego with fluffy platitudes and half digested ideas he had literally stolen from other sources which he claimed to be his own unique revelations, i.e. a pure Nietzschean will to power; this, while he held a knife behind his back which he plunged into his own brother's back. Mirza Husayn Ali Nuri is one of the ultimate case studies in radical evil, sociopathic nihilism and the dangers of such people. If he was the return of anyone, this man was the return of Cain. If a time machine could be built and one could go back into the past, I for one would not hesitate to go to 1850s Baghdad, find him and put him out of his misery right then and there for the good of all posterity at the very moment when he first began his mischief making against the Babis and Subh-i-Azal. The dark legacy of this malevolent scheister and his fraud has negatively touched a myriad of innocent people across generations and destroyed countless lives. As such Mirza Husayn Ali Nuri Baha'u-Shaytan was one of histories finest criminals, hucksters and con-artists, and who other than the dark one can possibly inspire and possess such individuals as he? And all of his true believers -- particularly those of them who have marticulated in his doctrine and climbed to the highest ranks of his cult -- are just like he is: dogged sociopathic nihilists engaged in radical evil.

Another ex-Baha'i wrote:

He was a cult leader. Plain and simple.

Baha'ullah was the farce to the Bab's tragedy. He was an opportunist who, like many others, made an attempt at capitalizing upon the popularity of the nascent Babi movement. He was clever in that he transformed the esoteric Shi'ism of the Bab into a religion which could have a more widespread appeal and an influence which could last long after the death of its founder, but this was perhaps his sole virtue. The means by which he further secured the success of his religion consisted of deceit, propaganda, murder, and collusion with sympathetic foreign officials.

He stopped at nothing, not even conspiracy against his own brother, in order to benefit himself. He stole ideas from other writers and supplemented them with his own "revelations" in order to make himself appear knowledgeable, when the reality was that he knew little of the intricacies of Islamic theology.

Whenever he was guilty, he passed himself off as a "Wronged One," and whenever he was innocent, it was not long before he would commit some other heinous act against someone who had done no wrong against him.

Subh-i-Azal appointed him as one of the leaders of the Babis and decreed that they should obey him, but Baha'u'llah was not content with this station, and so he began preparing "verses" and thereafter claimed "divine revelation." He gathered around himself a group of followers prepared to murder on his behalf and turned them against Azal and his partisans.

Qahir, Seraj, Dayyan, Aka Jan, Sayyid Muhammad Isfahani, Mirza Riza...the list goes on and on. Babi after Babi fell in succession by the decree of Baha'u'llah and/or with his good-pleasure. It did not matter how innocent he was, or even if he was a companion of the Bab himself (as was the case with Isfahani), if someone stood in the way of Baha'u'llah, he was summarily dealt with.

As Avarih cleverly remarked, "Baha is not [Imam] Husayn but Hasan[-i-Sabbah] returned."

http://bahaism.blogspot.com/