Director Paul Weitz would have been better off adapting just one book, since the conflation of three novels (even ones in a series) rarely translates well (think of the disappointing Lemony Snicket's A Series of Unfortunate Events). Consequently, The Vampire's Assistant drags on for almost an hour before Darren is even made a "half vampire." And by the time he joins the self-proclaimed freaks, the audience isn't able to fully immerse itself into their intriguing culture because the action shifts to the battling vampire groups. There's a ridiculous montage of Darren hanging with his new friends -- flirting with Rebecca the monkey girl, jamming with Evera the snake boy, and eating barbecue with the entire clan. It doesn't help the bland characterizations that Massoglia says everything in an emotionless monotone.
Hutcherson, who was brilliant in Bridge to Terabithia, nails the insecure, impetuous character of Steve and deserves more leading -- not sidekick -- roles. The familiar actors in the supporting cast -- including Hayek, Jake Krakowski, Orlando Jones, and Willem Dafoe -- are frustratingly underused, while Tony-Award-winning actor Cerveris chews up the scenery as a jowly mastermind with a penchant for purple accessories. Reilly is, as expected, laugh-inducing, from his hilariously awful Ronald McDonald hairdo to his many quips about vampire life. Bits and pieces of the movie work fairly well, but as a whole, it feels much longer than it is, and it makes you wish it had been adapted into a TV series instead, where all of the characters could have let their freak flags fly, instead of being reduced to just a few sequences.