As for the audio commentary by Ian McCulloch is the same one from the Tokyo Shock DVD. McCulloch isn't a great commentator, given that the film was 25 years from the time of recording. I wish the parts where he goes quiet, that Diabolik's editor Jason Slater would have notes and information to say, but it's clear to me that neither of them were prepared. A great commentator would actually watch the film the first time and makes notes and things to talk about on the second time viewing it. That's why Bey Logan is still the king of commentators, he watches a movie three or four times before recording!
The most interesting bits from the Zombie commentary was that McCulloch was going bald, so the filmmakers was doing all sort of tricks to show a young-looking McCulloch (tricks like shooting from below, etc).
As for the bonus disc on the ZOMBIE Blu-Ray, they are all in 1080 HD, which is very nice because often the features on Blu-Ray are in SD. Lots of interviews from the creators and actors from the film. The mini-documentary on the Zombie convention ("Zombie Wasteland") is the best of all the little documentaries. Watching all of them should not last more than 30 minutes, at least it felt really fast when I was going through them.
Picture quality on the Blu-Ray is excellent. DVD suffers from missing lines of resolution (like it was 480i instead of 480p). I've included a side-by-side comparison of DVD (left) and Blu-Ray (right). Note the color correction and also his fingers. Sure, they're minor differences, so even on DVD it looks great. You have to remember this film was made in 1979, to have it look this crisp is pretty spectacular.