While I won't argue that DSR@4k (on a 1080p panel) makes ALL games look MUCH better, it does make ALL games better -- sometimes slightly and oftentimes dramatically. I have so far tried DSR@4k on:
Hitman Absolution -- major improvement on jaggies on character models, your suit lapels and tie are so much cleaner and not a zig-zag nightmare. Those funny disguises you can get into like the football mascot or whatnot look much much much better and more detailed.
Bioshock Infinite -- amazing improvement, extremely noticeable even passing the girlfriend test, char models VASTLY improved over the previous mess they were, weapons have much much cleaner lines, less jaggies on floor.
Bioshock 1 -- slight improvement and does give it a cleaner, crisper look with less jaggies but nothing groundbreaking, game is really starting to show its age
Metro 2033 Redux -- could not run in full 4k but able to do DSR at a lower res (still higher than 1080p) -- noticeable improvement with cleaner lines and char models
Don't think I've tried any other games but as noted every game showed some improvement and only the oldest game had the least improvement. And don't tell me it's just improved aliasing, as in both Hitman Absolution and Bioshock Infinite the game feels like a much crisper, more detailed, higher res game. My guess is the newer the game / higher res it was to begin with the greater the improvement.
A quote from someone else using DSR@4k for Bioshock Infinite:
"Just finished playing a Bioshock: Infinite session, about two hours worth ... all the while at 3840x2160 resolution on a 1440p monitor (Samsung S27850D) (... using DSR ) ...
And, I have to say, it looked pretty freakishly good.
Comes down to it, I think the whole DSR/downsampling thing is worth it if you can keep frame rates reasonable..."
hmm I did not have to use compatibility mode.
running a higher res is not going to make an old game look better. all its really going to do is get rid of aliasing for the most part. that is why I just laugh when people claim how much better games look at 4k. now dont get me wrong as games with bad aliasing can certainly look tons better but other than that the graphics look basically the same of course.