Shaykh Abu Zahra in the biography of Abu Hanifa (ra) writes
"Groups of Magians, Sabaeans, Jews and Christians and others entered Islam, their minds still full of the teachings of those religions, and their understanding of Islam necessarily being filtered through them. Some pretended to have faith out of fear of the ruler, concealing their old belief, and began to try to corrupt the Muslims’ deen, to make them doubt their own beliefs, and to introduce ideas and opinions for which Allah had given no authority. The fruits of their efforts appeared: there were anthropomorphists, zindiqs and many other groups. The Mu‘tazilites tried to defend Islam, and their Five Tenets were the result of their sharp debates with their opponents. The tenet of Tawhid was formulated to refute the anthropomorphists; Justice was to refute the Jahmites; the Promise and Threat was to refute the Murji’ites; and the Position between the Two Positions was to refute the Kharijites who said that anyone who commits a sin was unbeliever. "(Abu Zahra, 46)
Also what really impressed me was there unique methodology which separates them from all the Islamic schools.
Shaykh Abu Zahra discusses the unique methods applied by the Mutazilla. He states
The methods of deduction employed by the Mu‘tazilites were different from those of others among the Islamic Community and their deductive premises also differed. There were several distinct characteristics in the way they debated.
Point 1
The Mu‘tazilites avoided imitation and were averse to following others without investigation, examination, comparison, proofs and proper criteria. Their respect was for opinions and not names, for the truth and not the speaker. Hence they did not imitate one another. The rule which they followed was that every responsible person is answerable for the principles of the deen to which his ijtihad has led him. Perhaps that is why they split into so many groups.
Point 2
Also They relied on the intellect to establish their articles of faith, finding support for their positions in the Qur’an. They did not have much knowledge of hadiths because they did not use them for doctrine or evidence.
Point 3They took from classical scientific sources which were translated in their time. They borrowed from some of those sciences and used them to support their arguments in clashes with opponents in the field of kalam. They were joined by many Muslims educated in the foreign education and philosophical systems which were nurturing the Arab intellect in that time, which is why there were many distinguished writers and philosophers among them.
Point 4They excelled in language, eloquence and clarity of exposition. Their men included eloquent orators and debaters who were skilled in debate, knew its rules and were experienced in its methods and how to defeat opponents. Their leading figure, Wasil ibn ‘Ata’, was a notable orator." (Abu Zahra, 46)
In comparison to uniqueness of the Mutazilla I give a preference to them on the 3 out of the 4 points above. I think all school today suffer from at least one of the above. When it comes to imitation, the Ahle Sunnah and 12rs are both proponents of it. Today both schools followers consist of followers who are blind followers of taqleed. On the contrary, the Zaydis, have not suffered from this problem, since their school of opinions is not restricted to one monolithic group or on the basis of taqleed.
When it comes to ahadith, I would have to speak against the Mutazilla for lacking education in the area of ilm-e-rijal. The 12rs try to substitute this area, by simply applying rational reasoning(aql) toward ahadith. On the contrary, if this is the case then there can always be opinions on the contrary. For example in Nahj al-Balagha the sermon of Shiqshiqiyya is widely quoted by the 12r to dismiss the legitimacy of rule held by Abu Bakr (ra), Umar (ra) and Uthmaan (ra). Since, Nahj al-Balagha, has no chain the only method they use to authenticate this sermon is through their rational reasoning. On the contrary, the Mutazillah have recognized this sermon through their rational reasoning came to another conclusion. Ibn Abi al-Hadid al Mutazilli (ra) recognized al-Khutbat al-Shiqshiqiyyah as genuinely attributed to al-'Imam
Ali (as), he, however, tried to interpret it in accordance with Sunni belief in the legitimacy of al-Khilafat al-Rashidah. The Zaydi in the area of ilm-e-rijal are still unknown to the majority of the Muslim world. On the issue of Imam Ali (as) caliphate not all of them say Imam Ali (as) position is was an explicit one. However, through his merits they point out that Imam Ali's (as) position of caliphate was implicit which is not disagreed by many of the Scholars of Ahle Sunnah. Both Shia sects Zaydi and 12rs invite the Sunni schools to recognize the Imam of the time. The 12th Imam of the 12rs has left the world for over 1000 years. Until he doesn’t appear people really have no “infallible imam” to rely on. This mean the 12rs expect Muslims to follow a system of imamate which is no longer functioning. Zaydis on the contrary also suffer from a high level weakness in this area. Their main weakness is that they have not established their schools in the Western nations. Their main imams of knowledge can only speak in Arabic and have sources which are also restricted in the Arabic language.
When it comes to scientific knowledge, once again I believe the Muslim world lack in this area. Today’s society of Islam is either filled with Muslims of worldly knowledge or Muslims of religious knowledge. There seems to be no balance between the two.
Shaykh Tahir Ul Qadri in the clip below identifies the roots of terrorism within Muslim lands.
Next Shaykh Hakim al Quick lists the weakness of the Muslim scholars.
Imam Al Asi points us that we have more fiqhi scholars in comparison to scholars who are scientist. He says the Quran has more hints toward science as comparison to fiqh.
As for the last point, I believe the early Mutazillah were closer to the school of Ahlul Bayt (as). However, the later Mutazilla started to deviate toward the wrong direction. Orators are needed the Muslim world, but if they lack scholarly knowledge then they are not different than the non-Muslim who present their ideas.