Hmmm, not imcomprehensible. But they changed several salient points, which in turn stood the whole message of the book on its head and improvised a new ending. (You know, the way they do.)

I actually enjoy it for the sheer swashbuckle effect (and Guy Pearce being squinty and evil, woo!), and because I am a sucker for any adaptation of this story. I'm pleased to hear I can finally get Gankutsuou from Netflix.