I get that UE4 has a lot of improvements for the developer side of things, but honestly, I don't think the average gamer is going to see those improvements. I'd really like to see more of the improvements that the end user can appreciate, which those UE4 screenshots... don't really show off, tbh.
UE1 -> UE2 was an obvious jump. Environments were much less blocky. Textures were higher resolution. Models were smoother.
UE2 -> UE3 was another obvious jump. Improvements in shader technology and hardware power made environments pop out even more than they had in UE2. The improvements in texture resolution and model polygon-count and detail were immediately apparent, as well.
UE3 -> UE4... is not at all obvious from a glance.
It's kind of telling that we now have to wait for a video to see these apparently obvious enhancements. That's not really a good sign, especially because, at many retailers, you're not going to have the luxury of video on your box to sell just why your new game is improved upon your old one. People will very likely just look at the screenshots and see what most of GAF was seeing in the UE4 thread - it looks pretty damn samey. Why should they spring several hundred dollars on a new console when the outputs it provides are so similar to what they're already getting? (I mean, I'd probably pick up on the improvements in AA, image resolution, etc, but there are plenty of people who won't, and even then, I already have a gaming PC for the most part.)