I have a Sony XBR65 810C that recently upgraded to 6.0.1 (or at least that's what it shows as current version) since the update, I have been experiencing some annoying bugs accros some of my most used apps. YouTube frequently stops showing or freezes the image while the sound is still playing fine. Amazon now has constant stutter making it annoying to watch any of the movies. Also they removed the duplicates from my apps list and put them on the featured apps, but there is no way to organize that section so I constantly have to pass all the useless apps I don't even have installed to find HBOnow.
The UI might be a little better but currently it's a horrible mess that's not optimized for my TV. I am looking for a way to reinstall the previous version of lollipop, since it was at least useable then. I'm not sure if it's even possible since the official Sony site warns you can't revert back but I'm hoping someone has found a way to do it anyways.
Sorry if this is an answer that is on the wiki. I'm currently only able to use mobile and the wiki doesn't load.
Once try doing factory reset and check if issues solve..