It's not so much a new feature as an enhancement to an existing one. It lets you can hear the results of upsampling in real time so you can decide whether you need to do it or not. Depending on the plug-ins you use, you may not need it at all, or you may need it a lot...now it will be easier to find out.
After mixing an album with upsampling applied when needed, I have no doubt that it can create a noticeable sonic improvement. Given that a DAW's task is ultimately to create audio, that's significant. I'm not a fan of the "wooliness" of foldover distortion.