Researcher Chris Patil of Ouroboros recently posted a skeptics' view of modern cryonics:
I’m a cryonics skeptic of the "extraordinary claims require extraordinary evidence" flavor. As I’ve said before, I suspect that long-term preservation of the potential for life by freezing or other means is physically possible, but at present I don’t think we’re making any significant progress in that direction.
It wasn't clear to me from his post whether he was aware of the state of the art in vitrification of tissues at low temperature without ice formation; those who write within the cryonics community are careful to distinguish between vitrification and freezing, which are two quite different things. Suppressing the formation of ice crystals at low temperatures is key to preserving the sort of fine structure in the brain that encodes the data that is the human mind. I said as much in the Longevity Meme news, and Patil later let me know via email that, yes, he is aware of vitrification, but not convinced that the evidence shows it does preserve fine structure sufficiently well at the present state of development. On that we can differ.
However, I do agree that, for all the sterling efforts of the folk at 21st Century Medicine and other groups, progress is slow in this field. It's the standard story of too few dedicated people and too little money. That is something that I believe is best changed through the development of profitable side-lines based on technologies developed for cryonics, such as the use of vitrification for tissue storage, for example. But the state of cryonics as an industry and a community is a whole separate post.
Over at Depressed Metabolism, I see that Aschwin de Wolf has penned a response to Patil's post:
The biology-of-aging blog Ouroboros has posted a skeptical post about cryonics that is highly representative of how most biological scientists respond to questions about cryonics. The discussion of cryonics is largely reduced to a discussion of the technical feasibility of suspended animation and resuscitation requirements. But suspended animation is not cryonics. Cryonics should be discussed in the broader context of decision making under uncertainty. People who have made cryonics arrangements are more than aware that contemporary science is not able to vitrify and resuscitate a complex organism. To them the central question is whether we can reasonably expect that future technologies will be able to repair the injury that is produced by contemporary cryopreservation technologies and rejuvenate the patient.
You should read the full text of both posts.