Its a great idea in theory, but again, not great with macos.
I've been running mine in 6144x2560 with apps zoomed meaning it works well for what I want - a massive single workspace with loads of room for windows. The format of the screen works well as intended - effectively a central large monitor with two portrait 27".
At that resolution though, I found it a real struggle on my eyes, no matter what distance I sit from the screen. I guess the lower-than-retina PPI doesn't help either.
I couldn't get any more useable resolutions with better display to be honest. The split-screen mode works really well, for once I could genuinely have a macOS and windows machine connected side by side on the same screen with very useable resolutions on both halves of the screen.
I also had a couple of issues. One is the refusal to wake from sleep without power cycling the monitor. This was a known issue apparently resolved with the latest firmware update, but that didn't fix it for me. Very annoying to have to unplug the screen when you're just trying to wake it up.
The lack of power from the usb-c ports on the rear of the monitor was annoying - I couldn't run my webcam off it. But I think that's my bad for assuming I could, I think the product listing shows you can't do this.
So it's going back, primarily because of the "wake from sleep" issue. Its one of those things I could just hope they fix with further updates, but its a big gamble given its cost.
In some ways, the story of this monitor as a Mac user is the same as I've experienced on pretty much any non-Apple, large format screen I've tried. The macOS scaling issue kills it for productivity as you either end up having a high-res with text which is too small, or a nice resolution with high-res text, but not much useable screen space.
Which I think could be fine if you're music/video editing and just like to have one app running full screen, but it kind of sucks for anyone who is wanting multiple apps running at a useable resolution.
Build quality is great, it's a nice understated design, the 120hz mode is great for productivity and casual gaming, it's an incredible screen, speakers are pretty good too, but the same Mac limitations persist. Which isn't Dell's fault, but the issue with sleep seems like a very fundamental one which shouldn't be difficult to get right these days.