For me the "comedic" elements like the whistle or the window-lick in part 2 worked very well, made the demon seem borderline nuts in addition to being evil. I think those elements gave The Creeper a much more unnerving personality; he doesn't take things too seriously, which is unnerving because among the "things" he doesn't take seriously is the fact that he eats people to rejuvenate himself.
I wrote a whole paper on analyzing the personality of The Creeper. The whistling, the window-lick the almost sexual attraction he has towards young men may in fact be Victor Salva channeling his own demons out of him by imprinting them in Jeepers Creepers. That's what I love about this villain; there's a possible mythology behind him.
Lets face it , it's fun to watch so bring on #3
I love those movies so Ive been waiting for 3 to come out