My first impression of this single was that it was pretty good, but worse than everything on NtAE. I felt disappointed to hear something so upbeat and accessible after how dark and grimy the previous EP was.
Now, after listening 50+ times, I think this is almost certainly the best NIN single since Closer. It's a cogent and energetic call to action, and it succeeds in ways that similar songs (THTF, I'm looking at you!) fail. The building intensity in this one feels both subtle and obvious at the same time. It's really impressive. A safe song, to be sure, but it's a really damn good one. It's the type of song that TR could write in his sleep, but he stayed up to work on this one anyway.
Now, will I be disappointed if the rest of the songs on Add Violence are really similar to "Less Than"? Most likely. But I would be disappointed with any NIN album that sounded super homogeneous.
Usually, every album seems to have one song that screams "The Single." Maybe that's just a way we've been conditioned as consumers of music, but that's beside the point. My point is, if this is the song that screams, "hey! I'm the single!" or, "you gotta play this one live!" within the entire project... then it's fulfilling that role extremely well.