"Well, honestly, I'm not a massive fan of courtroom dramas"

In this quote, Gabriel Macht is revealing his individual opinion about courtroom dramas. He specifies that he is not a "enormous fan" of this genre, indicating that he does not particularly enjoy viewing or participating in courtroom dramas. This could be due to a variety of reasons, such as discovering them uninteresting or not being drawn to the intense and typically remarkable nature of these kinds of stories. By utilizing the word "truthfully," Macht is stressing the genuineness of his statement and making it clear that he is being honest about his feelings towards courtroom dramas.