As I made pretty plain the first time around, I loved this episode. In fact, it wouldn't be going too far to say that it just might be my favorite episode of the new series, and the one that finally sealed two suspicions that had been growing in my mind:
1. I prefer Ten to Nine; and
2. I would like to whack Rose upside the head.
Both those statements require some qualification, however. I find Ten more authentically, classically, delightfully, convincingly Doctorish than Nine was -- not that I ever disliked Nine or doubted that he was the Doctor exactly, but something about the leather jacket and the cropped hair and the superficial toughness never quite rang true for me. Eccleston is a splendid actor and I don't think casting him to launch the new series was in any way a mistake, but he was quite markedly different from his predecessors in many ways. Whereas with Tennant I'm feeling more like, "Oh, yes, this is what I always loved about the Doctor." And yet, as others have pointed out, that burgeoning hubris and that diminished capacity for mercy are quite un- Doctorish qualities in a lot of ways, and there's bound to be a comeuppance somewhere down the line.
As for Rose, I don't mean that I want to injure her in any way, so I wouldn't want to whack her with anything too harsh. A big, wet, fairly fresh flounder would do nicely, though. She's so "Wah! It isn't all about meeeee! Why isn't everything about meeeeee?" and I really don't have a lot of patience with that. Sure, she's been through a lot with the Doctor, and he really ought to have told her he'd had other companions along the way (although considering how ready he's been to invite others along for the ride, you'd think Rose would have been smart enough to figure that out long before this), but I'm finding her possessiveness and petulance quite irritating at times. Especially in comparison to the splendid, classy, elegant woman who is...
My Sarah Jane. Oh, Sarah Jane, I always loved you, even when I was a child, and I love you even more now. Sure, the "I waited for you" stuff was a bit of a retcon, but I don't think it's too extreme of one. In an emotional and romantic sense she may have been waiting for the Doctor, but the fact that she's still working as a journalist, still investigating, still courageous and proactive, makes pretty plain to me that in other ways she certainly has been going on with her life. She isn't a pathetic figure, more of a faithful and hopeful one, IMO. She believed in the Doctor so strongly that she felt sure he would come back one day.
Also, if I could look even half as fabulous in my late fifties as Lis Sladen does? My word, I'd take that any day. I have never looked that good in a pair of jeans, ever. And her hair is lovely. She turned in a terrific, moving, very believable performance in this episode, and the chemistry between her and Tennant really sparkled. I realized a couple of weeks ago that I'm not so much Ten/Rose as I am Ten/Anyone, but now I think I might have to amend that to Ten/Anyone-but-Especially-Sarah-Jane. Because she is just that smashing.
K-9!!! As a kid I thought he was annoying and an insult to my intelligence as a young viewer ("Do they really think I need some silly robot dog to make me watch this show? As if!"). However, I was almost as delighted to see him as Ten was, and even though he didn't have a whole lot of screen time, I found his final sacrifice very touching. Plus, having him there brought the unexpected delight of seeing Anthony Stewart Head stop chewing the scenery long enough to snarl about the "shooty doggy thing" and that was too splendid for words.
Oh, was there a plot? Well, not much of one really, and what was there didn't make a whole lot of sense. However, unlike "New Earth", the characterization and dialogue in this episode was so fabulous that I honestly didn't care what the characters were supposed to be doing or why, so long as they kept on doing it. David Tennant was clearly having the time of his fannish life with this episode, too -- at his first meetings with Sarah Jane and K-9, you could practically see the "ZOMG!!!" written on his forehead -- and I found his unbridled delight in the whole exercise contagious.
A perfect episode? No. Have there been better written ones? Certainly. Nevertheless, it was the first episode of the new series where as soon as it was over, I wanted to go back and watch it again -- not just select bits but the whole thing from beginning to end -- and for me as a viewer, it really doesn't get much better than that.