Before actually playing it I remember thinking that Curse wasn't going to be very good (different mood, not sure where the storyline would go after LCR, new visual style, etc.) but it ended up being one of my favourite adventure games. Also, given the obscure/open-ended/abstract/jokey closing to LCR they had to work with, I think they did well with the continuity.
But I do think MonkeyMania's idea for MI2.5 needs to be made officially.