For me, the only downside was that my Epson print driver became Airprint, which is Apple's take on what I want (and I don't). I had to reset the printing system, download the driver from Epson, and reinstall it. That happened not only when I upgraded from Catalina to Big Sur but also when I updated from 11.1 to 11.2. and again when I installed the 11.2.1 supplemental update. The procedure only took a few minutes but it is annoying to have Apple dictate which driver I wanted.
The icons in Safari look different, the application icons look different, and the fonts look different. I'm used to this now, so it's not a big deal. On the plus side, some wonky behavior in Mail seems to have been fixed with Big Sur.
Hopefully, you'll like it and not have to call it Bug Sur!
