Cryonics almost certainly works. They use chemicals which prevent the formation of ice crystals. Which is like 90% of the reason most animals can't survive being frozen. They've demonstrated certain organs can be revived from cryopreservation - a rabbit kidney was frozen and then successfully revived. Which is incredible. And even if we don't have the technology to revive everything today, I do believe it will be possible in the future. The point of cryopreservation is that everything is preserved completely. The information in your brain - what makes you you, is preserved.
Until then I'm going to insist it's a cash grab because it's completely unproven.
Unless you are claiming that technology is going to magically stop advancing right now in 2016, it's a good idea to get cryopreserved.
I like the idea but this seems highly impractical. "Some people," in this case likely means a tiny faction of a percent. I.e. those who nearly die of a disease for which a cure is less than a decade away. The remaining majority are huge drains on resources. It hardly seems ethical when so many living people go with out basic medical care.
It won't be long before they've mapped out the genome to the point where tools like CRISPR allow them to swap out broken genes or re-enable genes that were erroneously disabled. When that happens there's going to be literally thousands and thousands of diseases that go from a death sentence to an inconvenience.
Some conditions aren't immediately fatal, but you are living on borrowed time, and those people might benefit by being put in a form of suspended animation. Those faced with the choice between toughing it out to a death that's going to be undignified and painful and, where applicable, some kind of assisted suicide could have a third choice: Sleep it out and hope it works. If it doesn't, you still have the other options, but the decay could be slowed down enough you've bought some time.
If done right, torpor or something like it would be very inexpensive. You'd just need someone to monitor vital signs, no big deal, as there's no expensive cryogenic equipment involved. Just a cozy place to rest that's kept at a comfortable temperature and fresh air. I can imagine this is like the most chill "coffin hotel" you've ever been in since people only wake up once every few months.
What could work is developing some kind of human version of torpor (https://en.wikipedia.org/wiki/Torpor), slowing down biological processes to a crawl, which would not only help with space travel but could buy people enough time for medical treatments to mature to the point of being feasible. It has the advantage of being fairly common in the mammal world, so genetically it's a lot closer than, say, what frogs do to survive being frozen.
You can't buy decades, but you can buy five to ten years, and for some people that would be all the difference they need.