I got mine a week ago.
Wanted to try it for some time before I gave my initial impressions. Most people wait no more than mere hours, max a day before weighing in.
First, I did have a very small amount of BLB in the left side of the screen. I didn't notice it first but once I came closer to the screen I saw it. Other than that, uniformity is good and no dead pixels/scanlines or whatnot. In normal use, I don't notice any BLB at all. Even when watching movies. It's really a tiny sliver and it's quite weak. You have to stare at the monitor for extended periods of time in total darkness to see it.
The etailer I bought it from seemed to have a good batch. I've looked at the SweClockers thread for this monitor and basically everyone who bought from the same source was happy. So it's not that I was amazingly lucky, it was simply that whole batch.
The monitor is already quite calibrated out of the factory, but I did try with some of the settings I've found online. I wasn't perfectly happy with it, I prefer deeper colors over saturation and granted, my taste is a bit niche so I turned the brightness down a bit and mixed the colors slightly differently.
I've checked blurbusters frame skipping check and all the rest, and it's all working like it should. So that's the technical/QC aspect of it.
I went from a 1080p TN G-Sync panel(at 144 Hz). So the primary benefits for me were bigger resolution and IPS. I didn't expect to find the 1440p resolution as key in games and what I've found is that it largely depends. Some games like R6: Siege play well at 1200p at 27". Some games, especially older games like the DX9 title of NS2, look fugly as hell on 1080p or 1200p. It's 1440p or bust there.
I've noticed this too with Battlefield 4. Playing at slightly lower resolutions(in MP) is not too noticable, but it is in games like CS:GO or CS:S. I always play at 1440p in SP campaigns, but on MP, the frame rate can vary quite a bit. If you're fine with 60-70 fps, you can do 1440p with a 980 on high/ultra in MP games, but if you want 120+ fps for ULMB you either have to adjust the details down or adjust the resolution. I do either of those for those rare games like BF4 which are quite demanding in MP.
The IPS switch is a big deal, but not as big as the resolution. The TN panel I had was already decent, but of course TN has its limitation. I wouldn't switch back, that's for sure.
One unexpected thing was how much I appreciate 1440p for reading stuff on the web. The extra sharpness in text is really obvious. It's like going from 720p to 1080p in mobile. Of course 720p isn't terrible, but once you go to 1080p it's such a difference.
Size-wise, I like the 27" factor. I could see myself use a 32" monitor, but only with a VESA mount since otherwise the top edge of the monitor goes up too much.
One final thing, Asus' OSD for the monitor is top notch. I've read about it before and thought to myself "who cares about the OSD". Believe me, you will start caring once you see how good the implementation is and wonder how you could ever use the nonsense on your previous monitor.
Overall, it's a great experience. My next monitor is either going to be OLED, HDR or 32". Preferably all three. In my view, upgrading to a new high-end monitor is really like going to an SSD in 2010-2011. It was starting to become mainstream but was still out of reach for most people. Hopefully in 3-4 years time, what I bought for $599 will be available to the masses for $299 to $399.