I'm not sure that it is necessarily the 'worst OS ever', but my experience has certainly been that it is more buggy than any previous releases that I've used. I don't recall ever having as many issues as I have with this release - and each Mac seems to have something different...
I also think that Apple's management and support to resolve such bugs has become more obstructionist. I have lodged Bug Reports on a couple of serious matters I've experienced that has made one of my Macs unusable, but each time they are closed as 'duplicates'. Of course, the veil of secrecy kicks in and the automated response is that you do not get access to the duplicate report, so you have no way of knowing what, if any, the resolution is.
When I've questioned this each time, I've been told that they cannot give me the information from the other bug report for privacy reasons, but if the problem is still occurring, then lodge a new bug report. I do this, provide the SysDiagnose and within 48 hours the new bug report is also closed as a duplicate.
I guess it shouldn't matter anyway, as this particular Mac is running Server which we've now been advised won't be the same later this year... So the resolution from Apple appears to be that it is all just too hard so let's drop the product, at which time they can close the bugs by claiming it is no longer a supported product.