I did the CILS B2 exam last year here in Brazil.
When I was waiting for the speaking test, the teacher that was talking to us said that the toughest part of the test is that the student's speach is recorded and sent to Italy, and in other exams is the school that applies the test that gives you your score. He said that sometimes he can see that the student has a good level but is too nervous by the time of the exam, so he can judge better because he is seeing and talking to the student.
But he said that the grammar and etc of CILS is easier than CELI, for example.
The themes of my speaking test were: an interview with the two teachers, and they asked questions about me and my studies of italian language, why I decided to study italian, things like that, than I had to talk for 1 minute about the image that I had of the italian people and culture.