It is fine, but then again I update it often too late which is actually pretty bad. The problem is Nextcloud pushes new features and a high frequency schedule of releases with those at an alarming rate of speed. Perhaps for corporate environments it is not as big of a deal as a professional team can fix obscure bugs with their knowledge and experience on their mirrored test servers, but home users don't have these resources available and public community knowledge and bug fixes need time which that release schedule hinders.
I still wouldn't say it is bad by default, simply because somehow it runs pretty stable for me since a decade. Updates are a pain though with many breaking changes and little bugs.