I admit I didn't get into the Leviathan storyline as a child, but now as an adult I find it very entertaining. [spoiler]It sort of reminds me of Invasion of the Body Snatchers, the characters we have gotten to know and love (such as Barnabas, Elizabeth, David) are turned into cold, unfeeling, almost zombie like. And of course we have the non-Leviathan heroes (such as Julia, Chris, Quentin and Barnabas once he broke out of his Leviathan
shell) determined to save the day.[/spoiler]
I have also found that the 1840 and 1841 PT storylines weren't as bad as others have said. Not saying they didn't have flaws, but still I found much to enjoy about them. And as much as I love Barnabas I can't really blame Jonathan for wanting to play another character. After all just about everyone else on the show got a chance to play another character so why shouldn't he?