Haha I've never played the Lost Chapters, though they sound cool. I have played the entire run four times through, and I gotta say Darkwood and Bargate are still my least favourite parts. Everything else, especially the Arena, is my favourite
I hear the lost chapters is essentially twice the size of the original game. But I wouldn't know because I haven't played them yet. The annoying part is that the pc port doesn't have controller support for some odd reason .