Yep, that whole River Song arc was one of the lugubrious quagmires.
Even worse, there are so many moments in it that are just so great (the series opener is really solid, as is all of The God Complex) that just get bogged down by Moffat refusing to let things go. Remember how great The Lodger was? Well, have another one, only have it be one of the worst episodes you’ll ever see. And the end of The God Complex would have been great to let the Ponds go, but they just had to stick around and be boring for half of series 7.
This era of the show is endlessly frustrating. I’m glad it’s finally ended.