We all knew it was coming. We knew the Ponds were leaving, we just didn't know exactly how (even if it could have been suspected once the Angels were in the picture), and River's novel was quite a clever way to acknowledge this, one that makes foreknowledge work FOR the story instead of AGAINST it. The chapter titles were obviously a bit of a red herring, but it was interesting to see them play out anyway. The book and the gravestone were also fitting metaphors for fate ( yes, "it is written" or "it's carved in stone" are easy metaphors, but the script makes them work really well in context ).
The anger and desperation of the Doctor, battling against a fixed point in time, gave Matt Smith a chance to shine ( and I somehow hope he keeps Amy's glasses for a while as a tribute to her ) , and at the same time, the usual banter between him and River ( who gave us the best definition of Matt Smith's Doctor I've heard : "an ageless god with the face of a 12-year old") showed his more comedic side.
The Ponds were the first Companions I've met, so I liked that the episode was a love letter to them, with references to many previous episodes. The graveyard scene was a cruel joke for those ( like me ) who thought for a second that the Ponds would just quit to have a normal life ( I should have remembered last week's ending, "normal life" wasn't an option any more) but it was fitting that, one last time, Amy chooses between the Doctor and Rory, and the ending on little Amelia, closing the loop that begun with "The Eleventh hour", was a sweet note.