As I understand it, the Corona virus has a mortality rate at least several times that of the flu, which makes it significantly more dangerous. Although at least you recognize its virulence; some still believe the total number of infected will end in the thousands, not millions.
The current mortality rate (gross, against the number of
cases) is at about 1.5%, falling from 2%, in the official statistics. The number of people ill enough to require hospitalization, however, has been variously claimed to be 5 - 30%, and there were reports that up to half of those hospitalized were dying. We now have a clearance rate (full recovery of a tested infected person to test for no virus) of about 2.5:1 against the death toll, again trusting the Chinese statistics. That would imply 5 people recover for every 2 who die so far. Clearance rate is a definite upper bound of the death toll; we can safely say it won't ever kill more than 2 out of every 7 people, unless those numbers are completely fictitious.
Conversely the Spanish influenza killed somewhere between 6 - 15% of the people it infected.
The reality is that we won't be able to trust any of the numbers from China, of course, so whether it kills 1.5% or 28% of the people it infects is impossible to quantify at the moment.
As cold as it is, the cruise ship which is quarantined in Japan is going to give us the hard data we need to know how lethal this is, because we know exactly one sick person was onboard, we know when they boarded, when know when they became sick, we know when the first ten people tested positive, then the next ten, then the next 41 ... We will know exactly when those people become symptomatic, and we will be able to know exactly when they become contagious. Ultimately, we will know when they die, and when they recover. We will know how many of the 1,350 people on that ship get sick, how many die, and how many recover. And because it is a controlled environment where we can model everything including air distribution, we will have an excellent idea of the level of contagion. That's data the PRC doesn't have any power over, and over the coming days medical authorities around the third world will be greeting every report from the Japanese about the cruise ship cases with great interest and attention.