Yes, some people are against Mustafa Kemal (Atatürk) and his opinions. There are several reasons of that, I will try to explain some of them.
Abolition of the Ottoman sultanate
Grand National Assembly of Turkey (TBMM) abolished the Ottoman sultanate in 1922 and the Ottoman Empire officially ended. Some people didn't like the fall of the empire.
Abolition of the caliphate
However the Ottoman sultanate was abolished, TBMM elected a new caliph (a religious successor to the Islamic prophet Muhammad) in 1922. He was intended to be a spiritual leader, but not a monarch. Even after the republic was declared (1923), the caliph was in office.
In 1924, TBMM abolished the office of caliphate. In 1928, the constitution was updated and Islam was not the official religion of the state anymore. In 1937, "secular state" was explicitly mentioned in the constitution. Some religious people didn't like the secular state.
Transition to the Latin-script Turkish alphabet
An Arabic-script alphabet was used in the Ottoman era and the first years of the republic. In 1928, the modern Latin-script Turkish alphabet was established. Since the original Quran is written in Arabic, religious people didn't like this transformation too.
The division of opinion mostly arises from the conflict between Islam and secularism. It was existent even before Erdogan, but nowadays people are more courageous to criticize Atatürk and discredit the democratic revolution. Erdogan has an undeniable impact on that.