I'm glad they didn't make the gender change a big deal. They didn't play the meta game and try to justify the choice to those who doubted it, they just made a solid episode of Doctor Who which featured a Doctor that just happened to be female. I think that'll pay off.
As for the episode itself, as I said, I really enjoyed it. I think the new 1-hour format was a good choice, it gives them some time to let the mystery of the monster unfold, and have some more extended dialogue and developmental scenes for the characters. Speaking of the characters, I love Yaz and Ryan! I'm not entirely sold on Graham yet, though. He's a perfectly likable character, but it seems like he's trying to fill a Wilfred Mott role, and less effectively. Hopefully he gets a little more development in future episodes.
One more thing, I love the ingenuity of 13! They did a "No TARDIS, No Screwdriver" episode a la "The Eleventh Hour", and it really showcased 13's resourcefulness. Also, she's the first Doctor to build a Sonic, no?
