I've noticed recently how poor the quality of the DVDs is. I only got a HDTV two months ago, and when I watch an up-scaled DVD of Lost the image quality is so clear that it almost looks like real HD. In comparison, the image quality of TNG is faded and grainy.
Yeah, the picture quality is pretty bad. Same goes for the early seasons of DS9. Funny though, when you watch Part II of Descent
you'll notice a huge improvement in picture quality compared to Part I. For some reason, season 7 looks a hell of a lot better on DVD.