I could not tell you how many books I have on the P-51 Mustang. For one thing, I'd have to find them all, and at the very least my copy of the Ginter book on the P-51H seems to have disappeared; probably others have attained Free Range status as well. I bought the book shown below because it was only something like $5.
If evaluated by the typical standards for such books, it is quite disappointing. It says that the Merlin 61 engine emerged as the hero of the Battle of Britain, when in fact there was not even one Merlin 61 used in the fight. It says that the first model of the Mustang was the P-51A, when even kids in kindergarden knew that the P-51A was not produced until March 1943 and followed the NA-73X prototype, the Mustang MkI, the Mustang MkIA, the P-51-1, and the A-36, to use even a rather course method of differentiation. The P-51A might just be the least important version of the Mustang, its entire production run taking only one month and the airplane not seeing that much combat compared to the others.
As for technical aspects, the book simply mentions details such as the "Meredith radiator" without explaining what it was and why it was significant.
But on the other hand, the book takes a loooong view of the genesis of the Mustang, starting before the invention of the airplane! It describes how Edgar Schmued, head of the Mustang design team growing up poverty stricken in Germany and becoming fascinated by flight. And it covers other individuals as well, such as Tommy Hitchcock, who did much to promote the Mustang in the USA. And Robert Lovett, the Secretary of War for Air, who pushed for long range fighters.
So this book really is not a history of the Mustang but is rather about the people who brought forward. The actual airplane is just sort of a prop that the personalities revolve about. So it may well make a valuable contribution on that basis.
But don't read it for the nuts and bolts aspects.