Time will tell, but I would guess that the performance and visual problem is probably less drastic than GAF would be making it out to be. As with most games these days, whatever platform you play it on you'll probably have a good experience since you're not actively comparing it to something else at that time.
More reports are coming in saying that it's 30 fps on Xbox One, while the jury's out on resolution. Some are saying 720p, others are saying 900p, but nobody seems to have the tools to actually measure it, so I'd take that with a grain of salt. I just wish the developers would be open about this kind of thing. Rumors on the Internet are almost always worse than the truth, even if the truth is uncomfortable.
As for you ATB, that you claim not to be able to tell the difference between 60 fps and 30 fps tells me that you haven't actually played many 60 fps games. The difference is huge, though I have no problem playing games at 30 fps personally. For an example of of what kind of difference it makes, just look at The Last of Us. Most people found the PS4 version to be easier than the PS3 version (me included), and that's because of only two things: The improved controller and the improved framerate. It's not just a visual thing. A higher framerate also improves control latency, which means you can react quicker and make finer, more precise adjustments to your aim.
60 fps can be important for action games, but it doesn't really matter all that much for calmer games, like RPGs. Shadow of Mordor is an action game, so the framerate is pretty important.
If the rumors are true, the Xbox One probably has one advantage over the PS4: In many cases, locked 30 fps can make for a better experience than unlocked 60 fps if there are plenty of framerate drops on the latter. It does sound like the Xbox One is locked 30, while the PS4 is confirmed to be unlocked 60, but the PS4 version rarely dips below 60 according to reviewers, so the unlocked 60 is probably the best option in this particular case. That's not always true.