I think it was quite noticeable here. I never usually go for the compressed versions, but I did here because it's the one I saw first. I thought the image quality was way below par (playing on PC), to the point that I deleted it and waited a little longer for the full version. I was expecting it to be a case of reduced filesize for a non-noticeable reduction in image quality, but IMO, that was not the case.
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It's obviously not a massive difference, and capturing it in a still is more difficult, as it's more noticeable in the video and the "moving" renders (where zoom/panning is used, like in the screenshotted render above). Even in a still though, while a quick glance may not immediately show anything, you can see in the compressed version (right) it's not as sharp as the full version (left). It's especially noticeable here around Tris's jawline, eye, and hair. When the images are moving though, as I say, it's a lot more noticeable (to me at least).
I'm not saying this would/should make a difference for all players, and especially anyone playing on a smaller screen/mobile will be fine, but it made a big difference for me.