I lied. I'm not on Episode 11, it's actually Episode 10, but IMDb threw me off because it counts the Christmas Special as Episode 1, while Netflix does not. Just needed to clear my conscience.
So...the most irritating thing about this episode was the treatment of Latin. Because I, in fact, spent several years studying Latin (not that I'm an expert or anything) and the mispronunciation of "Veni, vidi, vici," and its use was frustrating, to say the least. (In Latin, v's are pronounced like w's, and c's are hard, so it would be Weni, Widi, Wicki, meaning, I came, I saw, I conquered) But I thought it was funny that every time they used a Latin phrase (that one excluded) it was assumed they were Gaelic. Celtic, sorry. Very similar though, in my defense.
But on to the episode! This episode was largely irritating to me because Donna just could not get it through her thick skull that the Doctor couldn't screw with time by preventing the eruption of Pompeii. It's like, have you never seen a time travel movie in your life? People screw stuff up all the time. And even when he explained it, she just wouldn't shut up about it. And then the part at the end (spoiler!) when they were leaving, you'd think that if the Doctor really does see everything as either fixed or in flux, then he would have seen that that family was in flux, and could be saved, and wouldn't have needed Donna to make him go back. So that was a flaw in the story. But whatevs. Good episode, otherwise. It was really interesting.