Even with the negative press about the camera, this is surprising, because you expect technology to march on. What I didn't expect was how much better the HTC camera in the "obsolete" ONE S is versus Motorola's.
This is mostly evident in low-light shooting, such as indoors. The HTC is much better at capturing detail, and usually exposes correctly. The Motorola introduces washed-out colours and grain, even after the so-called "update" that was supposed to fix these issues.
The pluses of the Moto X are many: better reception and call quality, better loudspeaker, LTE, bigger screen with 720p, nicer curved design that sits naturally in your hand, and updated software (though if you flash a ROM the last one doesn't matter).
Not that the ONE S is bad in any of these areas (it's not), but Motorola is known for its radios and call quality, and they continue that tradition.
The ONE S is still a great phone and I was planning on keeping it for another few months at least, but there was a recent price drop for the Moto X. Because I use my phone for emails and browsing first, as a phone second, and as a camera a distant third, this is still an upgrade for me. I am disappointed that Motorola/Google dropped the ball with the camera though.
If you use the camera often, keep the ONE S!