I've been using this for a while, and I think it's overall quite smooth. Something I noticed that disturbs me is that for most websites, the corners are rounded, but for some they're not. Take for example apple.com in the added screenshot.
I'm happy to see this, profiles are essential for me and the way they were handled before was just too cumbersome. I like that when I have multiple profiles open, there's a separate instance for each of them resulting in a separate icon in the macOS ...