As an album, It underperformed.
A flat out FLOP it is not.
Though there wasn't as much overhype as there was Born This Way (there really wasn't that much hype here), Gaga has GOT TO STOP with the bold, over the top comments. Enough with the "Album of the Millennium" talk,that's not going to help your case, even if made in a humorous way.Hopefully, she can learn from her mistakes and takes criticism into account so she can improve her skill (because, ummm...that's the way ART works) instead of agreeing with the delusional ass kissing sect of her fan base and surrounding herself with yes men.If she can at least do those things, IMHO, she might be a bit better off next era, if not she's going to be in for it.
Musically ARTPOP is great, success is also on her side. But she is just really messy and this era was not structured well, nor did Gaga tone down on her big talk about art and stuff.