I will give my impressions. I have mixed feelings about the phone. It is very smooth and fast to use, but everything else is just okay. I have the GS4, the One and and Note II and have previously had the Optimus and Optimus Pro, so I compare its performance to all of them. I have the black 16GB on AT&T. I got it on Friday.
The good. As I mentioned, it is very fast and runs buttery smooth. The lag on the Samsungs drives me nuts. If they did not lag so much, particularly the GS4, I would be totally satisfied with them, but they do lag, so I keep looking for the best phone for me. Although the X is a little smaller than I like (as is the One -- the GS4 is the perfect size for my hand (although it is too light)), it feels solid and is easy to use.
The bad. The notification vibration sounds terrible. It sounds like the phone is coming apart every time I get an email or message. It males the phone sound/seem cheap. I have had some issues with battery life that I am trying to track down (may be app related) and my battery life has not been as good as the GS4 or Note II. As I mentioned in another thread, I have had very high "Time Without a Signal" percentages -- as high as 46%. Every other phone has shawn 1 to 2 percent at most. I think the X is just measuring LTE connection because it has a signal whenever I look at it or try to use it. The screen really shows fingerprints and looks bad most of the time. As mentioned, I would prefer the screen to be 5 inches. It is just easier to read, type on and use.
The so-so. Everything else is just so-so. Call quality is fair. The One and Note II have far better call quality and the GS4 is marginally better. The X is much better than any of the LG phones. Signal strength is not quite as good as the GS4 or Note when I compare them side-by-side, but only slightly. 3-5 db. I use the phone primarily for business and Sense and Touchwiz have better apps for exchange email, contacts and calendar than the base Android. The stock calendar app is just not very good. I use Nova launcher and have found widgets to replace about everything else. I have only taken a couple of pictures and they are fair -- not terrible, but not as good as I have taken with other phones. I will have to take more to be able to judge the camera. The screen is okay. It is not as good as most of the other phones I have had, but it is not that bad. As others have said, you really do not notice it that much unless you are comparing them side by side. If it was a bigger screen it would be more noticeable.
I am still undecided on Active Notifications. For one thing, my phone somehow activated itself and drafted a lengthy email while in my pocket while I was coaching my kid's baseball team tonight. Thankfully, it was not sent or I would have had a lot of explaining to do. I use Swiftkey and it filled in words (rather than giberish), but the words of course made no sense. It works okay, but I find myself having a hard time trying to get it to light up once in awhile and not being able to view more than one thing at a time makes it less useful if you have not looked at the phone for some period.
"OK Google Now" is okay, but I do not see myself using it much. It is like the many things offered on the GS4 that I will never use.
I will continue to use it and decide whether I will keep it or return it. I am afraid I might not be able to justify buying it outright (as I did after trade in of my old GS3). We will see.