Warning: contains a lot of negativity
So, the Doctor gets a sword wielding Silurian and her maid/girlfriend, a Sontaran nurse, a bunch of other Silurians (who are they? where do they come from?), Jodoon, a 17th century pirate, his kid and a blue man to help rescue Amy and her daughter. The plan also involves Rory being tough at Cybermen for no discernible reason while CGI explosions go off behind him dramatically. He is also dressed as the Lone Centurion, although he only existed in the universe with no stars and should not be known in our universe. Shh, he looks good in costume and he gets a sword too.
Amy was kidnapped by a group of villains comprised of a military church, a bunch of headless monks and Travis Lady. They plan to use the baby as a weapon against the Doctor in a way that is never explained. Why the want to do this is never explained either, other than the fact they don't like the Doctor very much. Off course this will probably be explained in the second part of the series, only this viewer has stopped caring. These villains make the Doctor think he's won for a bit, before we all find out they did steal the baby after all. This does not seem to serve any purpose, other than making the Doctor feel really bad.
The episode mostly consists of various people saying Ominous, Symbolic, Meaningful things, whether they actually serve a purpose or not. There is no reason why River, for instance, cannot join the Doctor sooner, but both her scene with Rory and her appearing at the end are designed for dramatic effect, not narrative logic. People also keep going on about how the Doctor is dangerous or a warrior or whatever, but this is not in any way new and (as none of these people tie their statements to any particular incident) is not terribly interesting. What did the Doctor do to piss off these people in particular? Who cares, he's The Doctor.
We're all meant to be going "gosh wow!" at the shock revelation about River Song, but I doubt I'd be particularly moved even if this wasn't the leading "theory" on the internet. To be fair, I have never cared for River because Moffat rarely managed to convince me she's the awesome character that he tells us she is (he's rarely managed to convince me she's a character rather than a plot device at all; those would be the rare times she says anything that isn't either cryptic foreshadowing or innuendo), but even if I did like River I can't see how the fact she's Amy and Rory's daughter makes her more interesting. A character is (by definition) about what they do , not who they are. Yeah, the story isn't finished, she's going to be groomed to be a weapon, whatever. Like I said, I have now stopped hoping the story will make sense when All Is Revealed. Moffat has run out of credit with me regarding River's character, and I'm no longer interested in where he's going with her. When finished, River Song's timeline will be the exact four dimensional shape of a duck pond.
There were many instances of Idiot Plot, like the blue man who has up to that point been very reasonable (what was that he said about the instincts of a coward?) walking right at the headless monks claiming they wouldn't hurt him because they're old business partners. I'd come up with more examples, but going over the episode in detail is too painful. The Doctor has his own cot for some reason, which River remembers from being put into it for two minutes when she was a baby. Or rather her ganger being put into it. Oh and apparently you can make a start on a Time Lord baby by shagging in the vortex.
At strategic points we are distracted from the awfulness by the time honoured tactic of "look, a baby! Isn't it adorable!", which works in a desperate sort of way. The performances are also very good, but that only barely registered with me through the mind and soul numbing effect of the plot. To the extent that the episode had a plot.
tl;dr
I didn't enjoy the episode.