Just finished watching. Pretty good- not "Dalek" good, but pretty good. To me, this is the first episode of the season that really captured the old "serial" feeling of the Doctor Who's of yesteryear. I've enjoyed all the episodes so far, but this one really seemed to have the entire formula and pacing of the old series. Really enjoyable. The ending is a bit abrupt- I think this one would have made a great two parter- but overall very good. The mystery element is intriguing, the episode juggled the two storylines very well (the mystery of the space station and Adam's personal quest), and the storyline overall was very well executed and satisfying. A lot of interesting secondary characters.
The line about "walls of gold" along with the information, subjugation, and cybernetic elements had me about convinced that the Cybermen would be behind things.
There were a lot of really cool "easter eggs" in this one- the Doctor's semi-telepathic identification (from the first episode of the season), the Face of Boe (from the second episode). Space Station 5 seemed very similar to the space station from episode 2, especially the observation deck and the view of the Earth from space.
I have enjoyed the various companions and how the show has played up the traits that the Doctor looks for in his companions- Mickey (by his own admission) was not brave enough to journey with the Doctor; Adam is somewhat overwhelmed and then too overcome by his own ambition to be a suitable companion; Rose, by contrast, is both brave and unselfish... although next week's episode looks to test this theory.
No mentions of "Bad Wolf" in this week's episode, that I saw. Did anyone else catch it if it was there?