Currently delving into the bits later in the book--one thing that becomes painfully apparent is that the camerawork on principal photography was astoundingly incompetent.

Among other things, Richard Marquand and Lucas clashed over the issue of how many cameras to use. Lucas preferred to keep several cameras running at once, so as to maximize his options in the editing room. Whereas Marquand generally tried to determine how he wanted to shoot a scene in advance, using only one or two cameras, leaving little fallback option if the results proved unsatisfactory later.

Also, apparently some old film stock was used that resulted in many scenes having an uncomfortably bluish tint. ILM ended up having to fix the color timing on numerous shots, putting further pressure on an already hectic post-production schedule.

The book also makes clear how much Lucas controlled things during shooting: he was always on set, and not infrequently offered the actors advice that was contradictory to that of the director. Marquand's personality didn't help: he seems to have been very meek and introverted, and never really bonded with many of the actors. In other words, a perfect hired gun.

Other bits are interesting too--like the confirmation that Lucas wanted Luke to be dressed in black because at the time he imagined this was the costume of the Jedi Knights. Also we get to (finally!) see the script excerpt in which Obi-Wan refers to Owen Lars as his brother, as in the novelization.