Here is a pretty good forum thread about AW3821DW:
https://hardforum.com/threads/aw3821dw-nov-2020-with-gsync-ultimate.2002202/page-3
Few users there already have it. It basically confirms inaudible fan, usable HDR and very low bleed/glow, which is typical for 38" IPS, this is very good panel in that regard.
One problem though is that the display does not have gamma control (typical for Alienware) and there is no sRGB mode and all picture modes are extended gamut, so SDR will be heavily oversaturated. To solve that you can either enable HDR in Windows globally (it will then take the control over displayed gamut depending on the content viewed) or tinker with OSD settings.
I have a perfect unit of 38UC99 so I will compare the two side by side once I get AW3821DW and try to match them as closely as possible. Hopefully AW is not too messed up. I am a bit concerned because I had AW3418DW for few days and it's out of the box setup was absolutely abysmal and there was nothing I could do to get it anywhere close to 34UC98 I've used at that time. But these were different panels and here panels will be the same, just set up differently.
But we can already say that factory setup on this display is not going to be good. This is something that LG does very well in last few years, you basically doesn't have to touch OSD, maybe except for old 34GK950G which also didn't have sRGB mode. Alienware on the other hand is notorious for bad factory setup and it seems that nothing has changed.