Being the first FMV game I ever played (I was lucky enough to basically entirely skip that era of adventure gaming), GK2 only served to confirm what I had already grown to believe about FMV gaming, that it generally sucks balls.
For me, it's not even so much the FMV as the digitally manipulated photo backgrounds and sprites. It just completely kills the magic for me--real world photographs cannot capture the same level of interest for me as genuine hand-painted artwork. It feels cheap by comparison. GK2 would have been so much better with hand-painted artwork. SO MUCH BETTER. I love historical fiction, and GK2 has some really nicely researched stuff, but the presentation just kills it for me. I wouldn't really go so far as to call it "worst adventure game ever" though...unless I was trying to get a rise out of Cesar Bittar.