Dalek
Bear in mind this is the first time I've ever watched an episode of Doctor Who on its transmission date (it was technically after midnight in Britain when I did, but it was Saturday here), not counting the TV movie. This was also the first completed episode of the new series I've seen.
I've never seen a Dalek more sympathetic or more frightening than the one in this episode, nor have I seen the Doctor so frightening at times. The Dalek was right when it told him "You would make a good Dalek." It's amazing how intimidating a five-foot-tall pepperpot can be when properly shown/lit...... The Doctor's reaction to the Dalek when he first saw it was abject terror, which I don't think I've ever seen in the Doctor before. The fact that the Time War wiped out both Time Lords and Daleks may have had something to do with it, but it made sense for the setting. The Doctor then moved to hysterical, childish cruelty in his taunting of the Dalek when he discovered it couldn't hurt him. It was difficult to tell which was the villain at that point.
The Dalek's new abilities were impressive, though perhaps a bit too powerful; its ablity to absorb DNA(?) from anyone who touches its casing was odd to say the least; its absorbing power and regenerating its casing made more sense to this longtime fan. The ability to rotate the shoulder section makes perfect sense for Daleks (the speed at which it turned was terrifyingly fast); the internal force shield, not so much. As for its hover technology--it was worth the loss of one of the few sympathetic redshirts for the "E-LE-VATE" line. NEVER taunt a Dalek ^_- Seeing the Dalek use tatics to exterminate the ambush squad was amusing--with three shots it eliminated over a dozen guards (and a few out-of-their-element scientists with guns).
The Dalek and Rose made an interesting couple for the last part of the episode; her absorbed emotions confused the Dalek so it could not kill her, and she did her best to understand and reason with it (even going so far as to convince it not to exterminate Van Staaten, who deserved it). The scen with Rose and the exposed Dalek creature basking in the sunlight was beautiful (the creature itself being hideous, but that's beside the point). The juxtaposition of a calm Dalek and a homicidal Doctor made this work, and let the Doctor know exactly how badly he'd failed this time. Poor Rose was torn between her traveling companion and a lonely creature who just needed to be understood......
The human supporting cast were not nearly as impressive. Van Statten was a one-note caricature, a low-rent Bond villain. Goddard was memorable only for her similarity to her boss in personality. Adam (I think that was his name) was entirely forgettable, like Adric without the annoyance factor to make him memorable. When the most sympathetic human character other than tthe Doctor's companion is a nameless guard, there's a problem.
That said, I enjoyed the episode immensely. It was well-plotted and very atmospheric, looking better than some American science-fiction productions. They took care to at least attempt to maintain continuity; the Cyberman helmet they used was supposed to be an "Invasion"-era one (unfortunately it was one which had been modified for "Revenge of the Cybermen" so had vacuum-cleaner hose handles and a four-barrel gun in its forehead), which would have been the most blatant Cyber-attack on Earth by that time ("Tenth Planet" mainly involving Antarctica, few-to-no Cybercorpses left from "Attack of the Cybermen", and a presumed coverup by the Seventh Doctor in "Silver Nemesis"). Yes, it was a bunch of concrete-and-brick halls, but that was acceptable given the bunker's established origins. As a great man once wrote, "little expense had been spared to make it look as though no expense had been spared".
In terms of acting, Nicholas Briggs and Billie Piper provided the most moving performances. The Dalek was by turns vulnerable, manipulative, autocratic, and reasonable, with Rose linking the Doctor and the Dalek with her concern for both. At the end, with the Doctor pointing the rifle at the defenseless Dalek creature, Rose didn't know who to sympathize with; through her obvious confusion neither did the audience. Not since the first season of Doctor Who has the companion (or companions) been the focus of the series; the new series, however, focuses firmly on Rose and her view of this strange visitor from another time. Rose is in many ways the main character of the series; her reactions to events reshape the Doctor's feelinigs--through her, he's learning to feel again. Whatever happened in the Time War has done a great deal of damage to his psyche; right now he needs Rose to help hiim learn all the things he's lost.
If "Dalek" is what Doctor Who for the 21st century is, it's got a long future ahead of it.