This book by S. S. Krotov Physics contains only some hundred problem. Still it is most tough to solve.
Because it is originally a collection of physics problems from previous year paper of IPO (Inter. phys. Olympiads).
Students who are preparing for iit jee mains has no use but for iit jee advance also need not to solve this book as a must but if student searching a great book for his books library collection and need something challenging then they can fight with problems of this book.
After solving I E Irodov Problems one can try problems from this book not before it.
It will waste lot time and you will only able to read a problem and then need to sit a side and that not a feature of a problem solving student.
This is common case of this book but good this is that it has solutions given at last and your time will not go in vein and you will learn many new thing in physics that will help you to crack iit jee main and advanced exams
Good luck if you go for Krotov. I Appreciate book by S S Krotov.
Auther iit jee master