The two greatest practical hurdles to cryonics are organizational in nature, not technology problems. Firstly to overcome inertia and do the work necessary to sign up as a member of one of the cryonics providers, and secondly to evade all the potential issues and problems that might occur at the time of suspension. This is particularly challenging if death comes unexpectedly, but the cautionary tale I link to here illustrates another common problem. What if your relatives decide to overrule your wishes once you are no longer capable of enforcing your original decision? "In 2006, [Mary Robbins] signed documents giving the Alcor Life Extension Foundation of Scottsdale, Ariz., the right to cryogenically preserve her head and brain. She also agreed to give the nonprofit foundation a $50,000 annuity to cover preservation costs. Her daughter, Darlene Robbins, said her mother changed her mind in her last days because of the procedures that preservation would have required before she died, including tubes in her throat and nose, intravenous lines and medications. Mary Robbins signed new paperwork that would give her family the annuity, the daughter said ... Eric Bentley, an attorney for Alcor, said Mary Robbins didn't sign a written notice rescinding the 2006 agreement. He said Alcor wants to honor the wishes she expressed in that document." From the outside, this looks a lot like the family decided that they wanted that $50,000, and to hell with Mary Robbin's desires - but we will never know for sure. Those folk signed up for cryonics should learn from these events, and adjust their own arrangements accordingly.