The final verdict
Now that you've seen DSR in static screenshots, I hope you can begin to appreciate what it does. I'm not sure I'd say it gives you 4K image quality on lower-resolution displays, but DSR can offer tangible and sometimes dramatic improvements in fidelity. Other AA methods sometimes come close, as we saw with TXAA in our Crysis 3 example, but DSR at four times the native resolution offers the best image quality currently available without hacking somebody's drivers. The combo of 4X oversampling for every single pixel and soft scaling to reduce temporal noise is pretty spectacular.
Just keep in mind that it's expensive. Rendering a scene in DSR's 3840x2160 mode is at least as taxing for the GPU as driving a native 4K display. You'll want to use DSR in cases where a game, even at its highest quality settings, doesn't present any real challenge for your video card otherwise. Happily, the GTX 970 and 980 are fast enough that such situations shouldn't be terribly rare.
For those more demanding scenarios where DSR isn't appropriate, Nvidia has another trick up its sleeve known as MFAA. I discussed it briefly here in my GTX 980 and 970 review. MFAA promises the quality of 4X MSAA at the performance cost of 2X MSAA by employing various forms of dark magic. Unfortunately, we're still waiting for Nvidia to deliver a driver with MFAA enabled. Once they do, hopefully we can take a closer look at it, too.
I have to scale down my sentences to 140 characters in order to fit them on Twitter.