He was mistrustful and inflexible. But his actions against Jat, Sikh and Maratha rebels were totally justified, though he didnt have long lasting solution for the insurgencies beside military action. If he was not best ruler, he was not worst either.
About inefficient heirs, same can be said about Sher Shah Suri…his dynasty fell apart within 10 years after his death.
I think one writer of modern times who has done a lot of research and written at length about the Mughals is William Dalrymple. There are around 9-10 books that he has authored on the subject.