Mixed Emotions
On topic though, I don't think you can compare U2 to the Rolling Stones. The Stones since the early 70's right up to today have always been hit and miss, alternating between a heritage act and resting on their laurels. Is there any song on any album since Vodoo Lounge that any but the hardest of hardcore fans actually wants to hear live? Not the case with U2. Maybe the case with NLOTH specifically, but Vertigo's only five years old and is still quite popular on tour.
If you want to claim mediocrity from U2 since AB/Zooropa, you can; but that's not fact, just personal taste.
We're in pretty much uncharted territory with this band. Yes, their relevence is slipping, but hardly over. Probably the closest comparison you could make would be early 90's Aerosmith, who were coming off a string of hit albums after a long break into obscurity during the early to mid 80's. Aerosmith managed to stay if not relevent, at least a part of the scene up until 98. 2009 could to U2 be what '98 was for Aerosmith, though that's a stretch.
It'll depend on what happens next. Aerosmith faded away amid injuries and personal issues. It doesn't appear U2 are heading that way. The next "event" album (SoA I don't think would count as it's being billed as a companion piece) will decide their fate.