Difficulty of questions is good.

You can provide some theory at the begining of each chapter.

Binding of book is poor.

I guess final proofreading of the book is not done.

At some places questions are not correctly framed, they have grammatical errors.

In maths section I have just seen chapter 2 and I got two wrong questions.

Writer and publisher content in the book is of high quality but final proof reading is not done properly.