According to published UK government data B4/5 is more infectious, so hospital rates will climb, but the death rate isn't, so far.
It does not appear to be more serious, I just got Omicron again after my 10 Yr old brought it home from school, he's unvaccinated same as me, it's his second infection as well, the Thai wife got it again as well, she's double vaccinated. My son got a bad cough with flem for over a week, then the wife and I tested positive, both of us slight cough no flegm and were not sick, maybe slight fatigue one day and running nose with sneeze, but over it very quickly not even as bad as the flue, that's 2 adults and a childs story, we presume it's B4/5 as B2 we had 10 weeks ago and B4/5 is what is circulating in NZ at present, but they only issue you with a pack of rapid antigen test kits and of you go home and test yourself, most of my sons school friends tell him that they have it as well and it's school holidays at the moment and their parents don't want to report it, as then your locked at home for 11 days, this seems to be the norm with many of my friends and nobody seems worried, except the very elderly with other problems are still at risk.