Characterization of The Master kind of weird ... I'm used to him being suave, charismatic, and sinister ... rather than a giggling looney. Still, it was nice to get a glimpse of Gallifrey-as-it-was.
As someone said elsewhere, "The Master dying just to piss off the Doctor -- that works."
Nice twist about Captain Jack's peculiar form of immortality.
I do miss multipart stories. One 45-minute episode is just not enough to get your teeth into a good Doctor Who story. I freely admit that some of those 4-part and 6-part episode from the classic series were chock full of padding -- but the single-episode stories almost always rush by too fast, feeling like you're getting the "Reader's Digest" version.
"Blink" worked very well as a single-parter, I will say that.