I updated my Alita also. I didn't do any factory reset before the process.

No problems aside from my finger slipping from the upgrade button too early (before connecting to the USB) so I needed to go out of the setup menu (any long press - OK, short press - navigation trough menu) and shut down my reader again and repeat the process.

When inserting my SD card it detected it in no time and I didn't have to format it again which is great.

No visible improvements in performance or anything really but then again I'm not using default reader. There are probably some improvements there.

Btw, anyone have experience with restoring Tachiyomi library? I have tons of manga on my SD (local source) and it did restore the library metadata from backup json I backup-ed it to and the volumes are accessible but the cover images are empty. I tried clicking refresh library covers in advanced settings but there is no button and clicking on the text does nothing.