I suppose it might be useful if you're recording in a large room that's just way too reflective and you want a dryer sound.
Would probably work great if you needed just a little extra isolation when tracking several things in the same room; could serve as a makeshift gobo.
But I honestly can't see it being in any way a substitute for tracking in a good room. I can imagine things sounding very dead, hollow, and boxy in that thing. There's no real broadband absorption, so if you're tracking in a smaller room, it's just going to kill all of the high-end reflection and do nothing to tame the standing waves, so you could be looking at a very dull sound with uneven bass response. Would probably be no better than a walk-in closet.
Again ... I can see this being very useful in a larger room if you want to tame some of the reflectiveness for a given track.