There's far too much wrong with Opera One compared to previous versions for me to list them all. The main ones that are forcing me to stop using Opera are the ugly-as-sin white border, the scroll limitations, and the speed dial icons.
If I was on the team developing Opera versions I'd make it more customizable. It may take up more space on the drive but oh well. From games to business programs, people accept a little extra program size if it means the experience is more enjoyable. Just look at games like Diablo, World of Warcraft, CoD, etc.
I will keep Opera on my PC for a couple months to see if things get fixed. But for now I'm going to have to use MS Edge or Firefox. MS Edge is total garbage but it is better than this new Opera One.