Regarding the Lords of Shadow DLC, it is not worth it at all. Beat both new "chapters" in one night sitting. One's just a boss fight (literally that's it)and the other has some nice puzzles and you can play as Laura but it goes by way too fast. Also, even though comic-style animated cutscenes are something I'm a total sucker for and love, the ones in the LoS DLC seemed rushed and were obviously a substitute for the normal cutscenes from the retail game to save money. If youre interested in them for the story aspects just read the Wiki plots.
Oh well. Just my opinions.