I got my copy from Amazon yesterday; I've watched the extras, but none of the episodes. I'll be perfectly honest here by saying that I found the interview with Diana Millay a little creepy, but in a likeable way. Her comments on Louis Edmonds were surprising to me, as I had heard nothing but positive things. For those who don't have the set yet, she said [spoiler]that she loved him as a person, but as an actor, he, according to her, frequently stepped on her marks and often forgot his lines.[/spoiler]
Ron Sproat's interview was just sad. That poor man.
Malcolm Marmorstein didn't really deliver any new insights on the show, unless I missed something. I did quite enjoy his interview on Set 4, where it seemed he wanted to take most of the credit for the character of Barnabas and give little of it to Dan Curtis and none to Jonathan Frid.
Leonard Wolf's interview I honestly found a little boring. We've heard all of the stuff about sexuality and vampires before.