This entry will contain gigantic spoilers for T3, including discussion of the ending, so if you haven't seen it and want to, I recommend not reading anything after this paragraph. Non-spoiler summary of my reaction: I liked the movie quite a bit, much more than T2 though not as much as T1.
I was mighty dubious about T3 for a while. I didn't get around to seeing it in theatres; I didn't hear much good about it; I considered renting it a couple weeks ago, but looked at my movie list and realized that I really hadn't enjoyed T2 much at all. (Most people I've talked with liked T2 a great deal, but on questioning have revealed that most of what they liked was Linda Hamilton's muscular upper arms.)
But then Kam said she'd heard various people say T3 was better than T2, so I figured I'd give it a try. And it turned out to be fun.
What I liked least about the movie was the very long chase/action scene at the beginning. It was probably only about five minutes long, but it felt interminable and boring to me. Yes, I get the idea: Female Terminator has a big truck and can do lots of damage to Arnold with it. Let's move along. I'm not sure what makes the difference between an exciting chase/fight sequence and a boring one, but I found this one boring.
(This ties in interestingly with Rob S.'s long-ago remark that the primary attribute of an action-movie hero is not Strength, Intelligence, or Dexterity, but Constitution: the hero can just plain take more damage than anyone else and still keep moving. (See Die Hard for an excellent example.) Horror-movie villains are similar, of course. The terminators in all three movies, both heros and villains, are definitely in that mold: most of each movie consists of damaging them over and over again in small ways until they finally die. I imagine there's something interesting to be said about the horror/action genre-mixing here, and the reflection and conflation of hero and villain.)
What I liked most about T3 was that, rather to my surprise, I found it easy to empathize with the two human leads: John Connor, who's been told all his life what was coming, and who never really believed that he could escape it, now (ten or so years after his initial success, five or so years after seeing for himself that Judgment Day didn't happen on schedule) learning that in fact it still is coming, that (as T-101 tells him) it's inevitable; and Kate Brewster, much like Sarah Connor in the original (there's even a line that gently pokes at the Oedipal part of their relationship) having this whole thing dumped on her, and rising to the occasion despite the deaths of her loved ones and the impending end of the world. These are character types and situations that appeal to me a lot in other contexts as well, and I think the writers and the actors did a good job with these renditions of them.
In particular, I think Clare Danes does a good job as Kate; sure, she spends a lot of time screaming, but she's not helpless by any means: daughter of a general, she clearly knows how to defend herself against humans, and is mostly rather brave in very daunting circumstances. In fact, another thing I like about this movie (though I think it's true of the whole trilogy at least to some extent) is the strong female characters: I can totally believe that Kate will go on to become second in command of the rebellion (and I love the fact that T-101 obeys her orders and not John's), and I found Kristanna Loken as the T-X much scarier than Robert Patrick as the T-1000 in the previous movie.
I also like the humor. There are some very funny moments (including Arnold wearing a male stripper's goofy sunglasses early in the film), and I thought the movie was a nice continuation of the tradition of the first two. Various people have said James Cameron's lack of involvement set off warning bells and that those warnings turned out to be right; but honestly, if I hadn't known ahead of time that Cameron didn't write this, I'd have thought he did. (And I often like Cameron's writing a lot, mostly because he seems to me to have a fair bit of respect for and knowledge of science fiction.)
There were a lot of nice little touches. The scene in the mausoleum actually brought tears to my eyes (though that may just have been me, since anything involving someone's mother dying young of leukemia is likely to do that to me), and I loved the coffin being filled with weapons. The interplay between Kate and her father on the phone at the beginning set up the character relationship economically and well, without laying it on too thick. I thought the scene after the mausoleum, with the three of them trying to decide where to go next while T-101 checks out the weapons, was also really well done, though it was one of several moments when people stood around in one place after temporarily defeating the T-X rather than running like hell while they had the chance. And I loved the whole scene in the RV when we find out the backstory about why T-101 obeys Kate's orders. Cool idea, nicely executed.
I thought the best scene "in" the movie was the deleted scene on the DVD, the "Sergeant Candy" scene, in which we learn how the T-101s got Arnold's face. Very funny; I don't know if it would've really fit in the movie, but I loved it.
In the scene in which T-101 and T-X fight each other one-on-one at the military base (in the men's bathroom), I did find it a little bit disturbing (in light of the allegations of Arnold's behavior towards women in real life) to see Arnold beating up on a woman—but on the other hand, she's stronger and tougher than he is, and it's really more a woman beating up on Arnold, so I can't really complain too much about that.
Finally, I thought the ending was excellent. A complete reversal of everything. The whole movie kept talking about making your own destiny, and so I kept assuming we'd get a standard-issue Hollywood ending to round out the theme: John would deny the inevitability of the future, take control of his life, and achieve victory (even if only temporary) against the machines. But no: destiny is real, characters can't control the future. I had been thinking "Sigh, another dumb Hollywood notion of what computers are like, they're gonna go blow up the 'central core' and then everything will be fine"—but no, they explicitly acknowledge that the Skynet AI is distributed software and just plain can't be stopped by blowing up physical computers. Relatedly, I loved seeing (in the cut Sgt. Candy scene) that the military is using Cyberdyne patents; of course blowing up Cyberdyne in the previous movie didn't destroy their work.
I can see why people disliked the ending of T3: it goes against all expectations. It's incredibly downbeat, and it doesn't provide the final climactic race-against-time explosion that it's been promising. It feels a little like the filmmakers pulled a bait-and-switch, and I'm often annoyed and resentful at being fooled like that. In fact, just the other day I was saying to a writer (now I can't think where) that it's not a good idea to mess with audience expectations this way (setting up for a standard happy ending of the genre-appropriate type, then providing a more realistic ending) unless there's enough else in the story that the audience won't mind. In this movie, though, there was enough else to like that the ending really worked for me.
And I thought it was fascinating that the only one who evades predestination is the T-101. Yeah, there's a reasonably common trope in fiction of a born leader who wants to evade his destiny but has it thrust upon him, the story of a reluctant hero taking on the mantle of leadership, but I think more often in Hollywood movies the message is that individual free will triumphs over destiny. Here, destiny is just plain inevitable—except for the machine that supposedly has no free will. And given that Arnold is the big-name star in the movie, that leads me to think that the T-101 is really the protagonist of this movie, that John and Kate are kind of just spear-carriers fulfilling their roles. T-101 is the one who's given the moral choice to make, and who manages to rise above his programming.
Of course, that's not really true: what he really does is manage to shut down his compromised peripherals, and thereby fulfill his programming. This would've been clear if Kate had done what she should've done and given him an order while he was struggling to control himself. But his choice was presented as a moral choice, as a choice between predestination and free will, and I thought that was fascinating. (And I see why the moviemakers didn't have Kate give him an order: that would've taken away the illusion of free will, made him look more like he was still just doing what he was told.)
I looked at some reviews after watching the movie; they were mostly pretty strongly negative. Ebert was critical (though he said it was fine as fluff); oddly, he says it's dumbed down from the original, that it's a kind of goofy adventure version of science fiction, with vision compromised in favor of crowd-pleasing. Which just seems weird to me; that ending is about as non-crowd-pleasing as a Hollywood movie could be. As opposed to T2, which took the very solid science fiction/horror adventure of the first movie and turned it (I felt) into a heartwarming family drama about a troubled boy learning to look up to his surrogate father, blah blah.
Ebert also objects to the time-travel paradoxes (which he sort of did in his review of T2 as well); I find that I just don't care about time-travel paradoxes as much as I used to. The movie pretty much ignores the paradoxical elements, as well it should; if Skynet were worried about paradoxes, the first movie would never have happened. It doesn't especially bother me that everyone in the future appears to be aware of the timeline alterations that have already happened. And actually, I'm not clear on exactly what paradox Ebert is objecting to in T3; I can't quite make sense out of his comment.
Anyway. As you can tell, I liked T3. I would recommend it to anyone who can go into it with the right expectations.