This is a great mouse with excellent functionality. The quiet click feature is a nice touch, it's very comfortable, and both scroll wheels operate smoothly. I haven't tried the "flow" feature, so I can't comment on that, but overall, the MX Master 3S features work well.
That said, I had high expectations for this mouse, but I encountered some issues. The bottom thumb button is awkwardly placed, requiring an uncomfortable bend of the thumb to reach it. The 'thumb pad' button is also positioned oddly—far enough back that I have to adjust my hand to use it.
Additionally, when scrolling through web pages or documents, I noticed the page would sometimes jump back up.