Also often forgotten is that biology isn't like an on/off switch - will you come back the same way physcially? Mentally? Could you live with having lost some of your higher mental facilities?
Given the mental damage done by aging (http://www.gwern.net/DNB%20FAQ#aging), it is a fact that ~>98% of humans, given the opportunity to live with having lost some of their higher mental facilities, will in fact choose to live.
I don't expect to survive with my memories all intact unless I am very lucky. However the complete regeneration of missing parts and restoration of lost functions seems like a very solvable problem.
The fact that a large portion of cryonics funding will eventually go towards this kind of research and thus help non-cryonics patients who have brain injuries is a rather significant spillover benefit.