I mainly wish Lost World had made more of its message about conservation vs exploitation. It ultimately amounted to a series of cool set pieces, in my opinion; everything else felt rushed and underdeveloped to make room for them.
I'm ambivalent about the massive departure the film made from the book, but I do wonder how differently the film would have turned out if Michael Crichton had returned as co-script writer. The double-act worked incredibly well for the first one.