I have been a dedicated Opera user for nearly 30 years. Opera has gone through many changes since the days it fit on one floppy but this Opera One has changed so much and broken so much I am at a loss to understand why it was put in the regular update channel.
Here are some issues.
The GUI is radically changed, for example,
list itemSo much has been stuffed into the address bar that it pushes everything to the left, hiding the current URL
list itemThe "Quick Setup icon is in the bar, instead of to the far right where it was easy to reach without close attention when something needed to be quickly changed, for example, Light to Dark mode.
list itemThe built in reader view no longer indicates whether it is in use or not.
list itemIn the past, even though I was in dark mode, when I copied the contents of the page reader and pasted it into an email, it pasted in black on white. Now it pastes white on black. Which means I have to change modes when I want to send an email.
Old extensions no longer work, for example,
list itemSend via Mail crashes opera. (This is an extension from the Chrome store that sends both the page URL and Title to my default email).
list itemOther send mail apps from Opera's extension site, close the page being sent. That is very confusing. I look up and it is missing.
I do have an old Beta Developer version but that is not fully functional. For example, there is no force dark page mode. And I worry that it will auto update one of these days.
You might be amused by an essay I wrote in 1996 when I was using Opera v. 2.12..