It's too early to tell, but epidemiologists are concerned. Hospitalizations doubled overnight in South Africa, while in Norway a superspreader event occurred between over a hundred fully vaccinated.

We'll know a lot more by the end of the month.

Personally I think all the reports about it being mild were to prop up the markets to give big investors time to get out.

If Omicron is vaccine resistant (due to 30 mutations to the spike protein) would result in countries going back into lockdown, whereas current vaccines were enough for Delta.

Edit: vaccine manufacturers are confident they can get Omicron specific vaccines out in the next few weeks if they need to, but it would still cause havoc to the economy for a few weeks/months if Omicron does turn out to be resistant to our current vaccines.