First things first: the out of box brightness on this panel is 450 nits. This is far too much for an IPS panel without local dimming, which is why you see all these awful black uniformity photos.I've attached two photos taken in a dim room at 20 brightness, or about 180 nits. This is about as bright as I want in SDR in this environment, and honestly it's probably still too bright for most people.Pros:- 27" 4K means PPI is very high for a desktop monitor. This has pros and cons, but for gaming, the sharpness is good.- Very high DCI-P3 coverage. The box claims 90%, but the default out of the box coverage is >95%. This lets the monitor display intense colors that normal sRGB monitors simply cannot.- Good calibration out of the box. White point is only slightly too warm.- Freesync works well on Nvidia GPUs out of the box with Gsync compatibility- Good overdrive tuning with 'Extreme' setting at 120hz and beyond... but:- Has support for backlight strobing for motion blur reduction. Normal VRB mode offers a bright and vibrant experience, unlike earlier strobing monitors that are too dim or have color issues in strobing mode.- HDR video on YT, Amazon, and other services look great once WCG enabled in Windows and HDR mode is set on the monitor (see cons on HDR though)- Can run at 144Hz 10-bit mode with two cables, but HDR/Freesync/Gsync is not available. This means you're capped at 98Hz 10-bit or 120Hz 8-bit for HDR. This means you would only use the 144Hz mode for VRB in SDR mode.- Has 2 DP and 2 HDMI ports for all your connectivity needs.- Comes with a monitor hood. It can help with reflections on the edges of the monitor.- No fan! Thanks to 4K Gsync modules, this is now a pro to be included!Cons:- IPS panel means the pixels not on the horizontal or vertical axes are worse at blocking light. This causes the corners to glow. You'll see it in a dim room when the screen is mostly black unless the monitor is set to a high brightness.- IPS panel is limited to about ~1000 contrast ratio and monitor does not have dimming. This means HDR at 400 nits can't display the dynamic range required for a great HDR experience at that brightness. I recommend reducing HDR brightness to ~30 to prevent darker shades from being blown out. This reduces the effect of highlights, but I think the trade off is worth it.- No configurable overdrive with Freesync enabled. It locks to the 'Normal' overdrive profile suitable for 48-80hz which is slightly too slow for 80-120hz. I don't notice it unless dragging something over a dark grey background, but others may be more sensitive.- Default color modes have way too high of a brightness; Switching to HDR color mode sets brightness to max! I have to reset it every time.- OSD is slow to navigate. You can mitigate with two configuration hotkeys, but that's only two keys available. Consider installing the Acer Display Widget app to control the monitor instead.- 10-bit HDR is limited to 98Hz, but this monitor doesn't have the dynamic range to make use of 10-bits luminance and color anyways. I recommend sticking to 8-bit 120Hz HDR: there is no difference in experience.- 144Hz mode can be funky. It took several monitor resets to enable overdrive configuration, for example.- Awful speakers- Poor white uniformity. Both of my monitors had dim left and right edges which were clearly visible when browsing websites with light backgrounds.Other:My first XV273K had a backlight defect where the left-most edge would not light up fully to the same brightness as the rest of the monitor. Happy to report the replacement monitor has no such defect, and no dead pixels on either monitor.Conclusions:If you want the economical 4K 120Hz Freesync high color gamut monitor (not a 43" TV, for example), XV273K is it.If you want a more premium monitor (better overdrive for example) and run an Nvidia GPU, get the XB273K.If you want to experience the best PC HDR gaming available (outside of using a TV), go for the X27/PG27UQ.