Coronaviruses are a family of viruses that include the common cold, but a few have been known to cause more serious illness. The new coronavirus is said to cause fever and respiratory symptoms (cough, difficulty breathing,) with the BBC reporting that, as with most coronaviruses, it poses the highest risk of complications like pneumonia to the elderly and those with immune insufficiency. Of the nearly 8000 patients confirmed as of January 30, about 170 have died, most of whom had existing chronic health issues.
This new virus is novel and unknown, and we have no idea if it will subside with the onset of warmer weather, or if it will just continue to spread - so that's the big concern.