Watching the first season of Doctor Who the second time through on SciFi, the biggest surprise to me has been how conventional (within the series conventions of Whoville) the episodes are. The conventionality is primarily structural. Episode opens in strange time/place, a couple of characters are introduced, a dramatic event implies a much broader strangeness, TARDIS or Doctor appears, theme, title and credits. The differences are the hour format, which has a different rhythm and act structure than the earlier shows. The original series was a descendant of movie serials – episodes ran a half hour and the story arc generally ran 4 episodes. These were also distributed widely, especially in North America, in the form of edited (to trim the repeated sections used to introduce the situation in episodic format) movies running 90-100 minutes.
The other big difference is the intesity of the emotional landscape of the new series
And the humor. And the target audience is now adult, perhaps adults weened on Doctor Who, as I was.
That said, not sure what to make of the season 1 (new series) finale.
I meant to expand this. When I started writing, I thought that the hyped emotional content and the strength of the relationships was going to be the point. Then somehow I got carried off looking at the conventional elements. Having just seen the 2nd season closer I feel even more strongly that that is the clearest difference. The show seems to be as successful with the young audience as ever, though it IS written in more complex, adult style. Quirky humor, though, has been with The Doctor since the beginning, becoming prominent when Douglas Adams was the script editor and Tom Baker and Lala Ward flew the TARDIS.