i work with insights too, for the second year; what i can say about it is that the book has its ups and downs:it is full of mistakes , too many activities, redundently boring activities; misplaced activities(reported speech/inf & gerund)modals and ..........
yet the book has its good sights ,i personally believe that if it were covered students will find no problem while sitting for their exams, just do a little efforts to make things better,and it will work better.

The book is a pain in the neck. I never rely on it. Very often I resort to my own materials. My students find it too boring . I never ask my students about it.
It makes my teaching tough.