Animals with more sophisticated nervous systems than nematodes can survive vitrification.
http://www.ncbi.nlm.nih.gov/pubmed/20086136
Even more sophisticated neural networks, mammalian brain slices, can now be vitrified with present technology.
http://www.21cm.com/pdfs/hippo_published.pdf
Of course it is what happens to whole brains that are vitrified that really matters to cryonics. The only paper published so far on the technology presently used in cryonics applied to whole brains is this one
http://www.alcor.org/Library/pdfs/Lemler-Annals.pdf
with more micrographs from that study here
http://www.alcor.org/Library/html/cambridge.html
and many more here
http://www.alcor.org/Library/html/micrographs.html
Unlike slices, there is no expectation that cell viability is preserved in whole brains because the cryoprotectant exposure time is longer. However connectivity and extensive biochemical information is believed to be preserved, as these micrographs suggest. It is presumed, but not proven, that the effect of thermal stress fractures at cryogenic temperatures is displacement of fracture planes. This would theoretically still preserve connectivity information, although requiring hyper-advanced technology to do anything with that information.
I recently found something that may be of concern to some of the readers here.
On her blog, Melody Maxim, former employee of Suspended Animation, provider of "standby services" for Cryonics Institute customers, describes several examples of gross incompetence in providing those services. Specifically, spending large amounts of money on designing and manufacturing novel perfusion equipment when cheaper, more effective devices that could be adapted to serve their purposes already existed, hiring laymen to perform difficult medical procedures who then botched them, and even finding themselves unable to get their equipment loaded onto a plane because it exceeded the weight limit.
An excerpt from one of her posts, "Why I Believe Cryonics Should Be Regulated":