Westeros.org was pretty down on the episode, calling it the first genuine disappointment of the season:
Their main charge, boiling all of the complaints down, appears to be that the changes being made are far removed from the spirit of the books and, on their own merits, feel lacking in logic for the sake of ramped-up tension. They put forth some interesting points about certain changes in Harrenhal not quite making logical sense (the mis-delivered letter, the chase through the castle after Arya is caught with the letter, etc), and Qarth losing its more fantastical qualities from the book (it does feel a little stale, I'll admit).
To me this review sounds quite nitpicky, in a "I don't like the changes to the books" type of way. Despite their attempts to explain their issues with the episodes, every single argument returns to the "that's not the way the books did it" line. The complaint with the way the Littlefinger-Arya scene was staged seems particularly strange. A season and a half should be enough for even the most ardent fans of the books (of which I am one) to let go of arguments about changes. The show makes changes in a very considered way, having to deal with limitations that the page doesn't necessitate. I can't really say I'm surprised that Elio and company are sticklers for loyalty to the books - their work on the Westeros site is incredible but certainly indicates a devotion to the source material that would make any television changes detrimental to their enjoyment.
I think Ygritte's intro has been handled fairly well, and the actress seems to capture her complexity (toughness, intelligence, warmth, affability) well. The Qarth storyline has been boiled down to the very basics, for necessity's sake. There isn't enough airtime to fully explore the city, not with all the plot developments in Westeros and north of the wall to cover. And I can't imagine there not being attempts at stealing her dragons at every opportunity, so I'm cool with that development. I thought the way the Arya chase and the Jaqen kill were handled were fairly well done. The King's Landing riot was a little wonky at points, but again that seemed to be about money and space limitations.
Arya naming Lorch and the Tickler are about her lack of strategic planning. Those threats were more immediate. I think she hasn't named Tywin because she's not sure how it would immediately affect her situation, or that of her brother Robb. But the other two deaths ended the torture and kept her theft hidden, respectively. She can't see the bigger picture yet. Like Jmacq said, she's a tween with little perspective on the larger events taking place.