AS a stand alone dvd is it worth it?
I personally found it amusing at first, then got bored with it after about half an hour of continuous viewing. I think it's okay to watch part by part, since that's how the episodes on this 2 disc set were presented online in the first place. Some of the documentaries are cute, some informative, some totally useless. I stopped watching after about an hour's worth, with intention to resume at a later time, but I never have.
I think it's more a must-buy if you're a die-hard Peter Jackson fan or you really want to know the ins and outs of filming an effects-filled action film. But if you're just a casual moviegoer, then I think you can skip it. You won't feel it was worth the 4 hours of your life it took away.