I haven't been to Turkey but have heard good things about the people being very friendly in most parts of the country. My experience in other Muslim areas has varied a lot. People in Malaysia were welcoming regardless of ethnicity or religion. In Sri Linka, however, which is majority Buddhist with Hindu, Muslim & Christian minorities, the Muslim neighborhoods were noticeably less friendly than others. Other cyclists I met all remarked on it because the contrast was so clear. Tunisia was a mixed bag with young boys being a serious nuisance due to stone throwing and other unpleasant mischief, but adults being friendly.