I would describe this book as a non-linear history of Delhi from Iltutmish to Indira. It is definitely a very engaging read and many a times makes you want to jump out of the chair and get to the ruins of a random 16th century haveli at this very instant. The portions about the Mughals, especially Shah Jahan onwards are well researched and presented. The narrative is a bit sparse on the earlier Mughals and also on the history of the pre-sultanate period.
All in all, it is definitely worth a read. It will definitely make you go down the spiral hole of Wikipedia browsing several times.