Yes it's the DELL, it is an amazing monitor. I have watched some HDR movies on it and it looks amazing, it gets pretty bright. Same with games that have HDR features, The Division 2 and Far Cry 5 popped out of the screen, absolutely great. I have tried out HDR on some of the LCD monitors that support it but most of them don't get bright enough and still have IPS glow, even the FALD screens have haloing so IMO this is the best way to do PC HDR at the moment.
The monitor does have a fan and most people say it is inaudible, it is very quiet but I am a bit of a quiet freak and very sensitive to sounds/fan noise so I can definitely hear it when sitting in my quiet office (PC is almost silent). If I'm watching or listening to anything even at lowish volumes it is drowned out very easily.
It has an unusual pixel arrangement with it being QD-OLED and people have said that text isn't as sharp but to my eye this monitor looks sharper than the LCD I had.
Other than that I'm not sure I have really found any downsides, I even found it's design really nice, definitely a massive step up from my old Alienware and was worried the white would look gaudy but it is really sleek and very thin at the edges.
Edit: This is what Ultrawide has been crying out for IMO, top end ultrawides have been way more expensive than their 16:9 counterparts whilst being kind of lackluster. This being priced basically the same as other top end 21:9 LCDs just makes them all obsolete.