SPOILERS AHOY! After the break!
Just going to throw a few points out, as I know io9 will do a proper review by tomorrow or so. It was mostly a good episode, but a few bits annoyed me
* Clara: dammit she's pissing me off now. the 'on again off again' relationship bit is wearing thin. This trip is supposed to be a 'last hurrah' for her traveling with the Doctor, but in the end she lies(?) and says Danny wants her to keep going (which I wasn't ever clear that he had a major problem with her being the Doc's companion, more that she had been keeping things from him?)
* Pacing: it was great...except for scenes with Clara waxing emotional about the Doctor, or arguing with him, or whatever. The running clock of 66 seconds was a great visual though.
* The overall mystery was good: who is on the train, and ultimately why they are there. Also, how and why the people are dying, and in what order, and in the end what the mummy actually is (hint: it's a recurring theme in the season...)
* Good supporting cast: it was one of those episodes where I felt every major supporting cast had a point int he plot, and all were played by good actors.
* I did have a problem with a room full of experts yet only the Doctor, the conductor, the engineer, and the mummy expert are the ones talking for the most part. I guess you can only pay out so much for speaking parts per episode, due to budget constraints I'd imagine.
* What is it with DW wanting to recreate old Earth transport in space? The Titanic, and now the Orient Express? Is this a trend int he future or something?
* Some great dialogue: a fave bit was the psychic paper scene, and how Capaldi reacts to what the conductor sees. Brilliant Capaldi moment.
* This Doctor can be very cold, very alien. We see it again in this episode in how he handles those dying, during the 66 seconds. It's dark, it's brilliant, and Capaldi pulls it off wonderfully.
Overall a good episode, with only a few speed bumps.
A friend of mine thinks we'll be seeing Capaldi's Doctor slowly slipping to the darkness that will give us The Valeyard. I didn't agree at first, but the more I see of Capaldi's Doctor, the more I'm starting to wonder if this isn't the case. We shall see.