Shaykh ’Ubayd al-Jaabiree, retired professor from the University of  al-Madeenah, warned the Muslims against Yusuf Estes, describing him very accurately as:

”He is either astray, leading others astray, or he has lost his mind.”

Another scholar, Shaykh ’Abdur-Rahmaan Muhyiud-Deen, former Mufti at the Prophet’s Masjid, said:

”Astray, leading others astray… he does not know about Islam… Satan has spoken upon his tongue…

Source: http://ahlulbidahwalhawa.com/2013/06/15/yusuf-estes-and-the-shiite/