Frankly, I don't want more interactivity. I just want clean, easy to navigate menus for simple selection of what I want to watch. I don't want fancy menu transitions that take more time, and I don't want to have to play a game to access something or hunt for an easter egg.
Commentaries I like, because only the audio has changed, and I don't mind a trivia track either. With a trivia track, it's just a text overlay, so it's not that different from watching a subtitled movie, which I certainly can handle. What I don't want is something that's too distracting, like PIP where you have two video areas to follow. I would rather have the making-of footage separate from the movie.
I know people say that we need these fancy features to set the new formats apart from DVD, but for me just HD picture and improved sound (along with the existing extras) is fine. One thing I like so far is that the high resolution allows for all the features to be listed on one menu page instead of several pages as with DVD.