I know this is going to be a bit of a shocker, particularly to fellow Doctor Who fans, but...to me, River Song gets less interesting every time she shows up in the series.
I obviously don't want to give anything away for "A Good Man Goes To War", which hasn't officially aired in North America, but suffice to say that Big Revelations about River are in the offing. And like all the other Big Revelations about River Song, it seems to me to diminish her in my imagination just a little bit more. When we first saw River Song, she was a larger-than-life human able to hang with the Doctor on his own level, a woman who may or may not have been his lover (or even his wife) who has her own tremendous, exciting adventures that only occasionally intersect with those of the Doctor...and those not necessarily in consecutive order at that.
Now? She's that woman who lives in Stormgate Prison and breaks out every once in a while when the Doctor needs her. She's someone who lives life backwards to the Doctor, not sideways and upside-down and at crazy non-Euclidean angles. She's someone who, not to spoil "A Good Man Goes To War", has a specific and finite character arc that we have already seen, in a sense, the beginning and end of. It's hard to see her as an equal to the Doctor in that light. After all, he's a man with an unlimited past and a wide-open future. River is anything but.
I miss the River who wasn't anything but. I miss the River whose story couldn't be told on television because you can't hire an actress to time travel fifteen years into the future to pretend to be her own younger self. I miss the River who might only have lived into her forties (assuming she wasn't from an era where someone could live to be two hundred and still look like they were in their forties...) yet spent those years full of life and adventure, crossing paths with twenty-seven incarnations of the Doctor in her career as archaeologist, smuggler, burglar, professional jailbird, and dozens of other professions in a rich life filled with incident. Like the Star Wars prequels, River fails for me not because of any failings of Steven Moffat, but because the River Song in my head was mine and nobody else's is ever going to be as good.
I know that a lot of people aren't going to agree with this. They like Moffat's River Song, and I don't blame them. But I think if you could meet mine, you'd like her better too.