Following is a pretty long rant about this whole thing >.>... just warning you in case you just want to post your own opinion regardless of other's
First off, in general the finale was great cuz it's the finale. It also sucked cuz it means the Avatar series is over . And now my rant about why I liked it, where I think it could've been better, and my arguments to make you all agree with me XD.
For those of you who thought there "wasn't any character development": IT'S THE FINALE. Character development belongs in the main series, where we watch the character slowly change over time. In the finale, we watch the results of the development, the finale is the big showdown. The ieces have been laid down, and now it's a uber huge cool fight scene. The most a finale should ever have in regards to "character development" is maybe one of the more major characters changing sides or something dramatic like that. If everyone in the series suddenly changed in the big finale... it'd be weird >.>.
Azula VS Zuko: Great. Everyone knew the showdown was coming, and with Zuko now being a pretty awesome firebender due to having found the "original" source and with Sozin's comet amping there powers. Totally awesome. People who say it was DBZified, I totally disagree. Yes, the big fire blasts did take away a bit from the martial arts, but just look at some of the ways Zuko counters Azula's attacks. The two big parts I remember is the one where she sends a massive column of blue flame, and he seperates them with two outwards blasts. That, and the time he pulls the cool breakdance move and finally hits her. Yes there was less acrobatics stuff but hey, it was awesome. Totally unlike DBZ [did you see any of this "stalemate" pushing back and forth stuff? No!].
I can't remember who said it [the one with the Iroh avi], but I agree that the way Katara took down Azula was a bit unlogical/stupid. If she had them both stuck in ice, but she could still move freely, why not just get out of the ice herself and leave Azula frozen? Why go through the trouble of chaining her down and releasing the ice???
~~~
Aang VS Ozai: Out of all the parts of the finale, my least favoritie part. It was epic, I'll admit that, but the firejetting was annoying. REALLY annoying. It was OK with Azula, cuz she only glided around [none of that arial crap], but with Ozai and Aang it was stretching it a bit. It became a more "fly around and shoot at each other" sort of thing. Out of all of the scenes, that was the closest to a "DBZ" fight scene. The hamster ball especially bothered me >.>... I know I know, it just didn't seem very... aesthetically pleasing to me...
Out of that entire fight scene, I liked the "rock machine gun" and the bit where Aang was like "pah, you can launch three fire blasts at once, watch me do 5 bwahahaha!"
Oh and did anyone notice that in the "full" avatar state, it wasn't just two voices [his and Roku's] but ALL the avatar's voices?
~~~
Aang Didn't Kill Ozai: Now, it's not so much that Ozai didn't die that bothers me. And I don't think that's what everyone else is pissed off about either. It's how Aang, when it looks like he'd finally have to kill someone, just happens to stumble across a lion turtle who has another way. It seemed much to out of the blue, and it really ticked me off. Again, can't remember exactly who said it, but in the end, Aang really didn't change much >.>.
It's understandable because it's a Nickledon production; they don't want to kill people on TV, but it just seems unrealistic and all. Something no one else has mentioned but I'll point it out. Has anyone noticed that NO ONE dies in the entire series? If you know the character's name, he/she doesn't outright die. Or at least they don't actually outright point out "hey, he/she's dead."
Try it, think of any character who's name you know who you know for sure DIES.
I can only think of Admiral Jow. He is drowned to death by the funky moon/Aang spirit thing at the end of season 2. And maybe "SparkySparkyBoom Man" but that's not certain.
Anyways, point is, it's a show that kids will watch, we can't kill people on them, and we can't say anyone deserves to die. It's unethical, especially for a series like Avatar which is really deep in that sort of thing.
The only thing I'll say in favor of the Lion Turtle [because although I understand that they couldn't have Aang kill Ozai, it PISSES ME OFF], is that if anyone else will notice; he's the ONLY character in the ENTIRE series who has human eyes. Every other character is animated as normal, but they gave the Lion Turtle realistic eyes. Kinda kooky XD
~~~
Kataang and Maiko: I'm A OK with all the relations. And personally, I'm kinda ticked off at the people who are all like "No! Zuko and Kataraa! No! Zuko and Toph!"
People, the series was PRETTY clear about who gets together with who. Sokka ,Suki, and Toph will forever remain outside of the "deep emotional scenes." They have a few, but I think they're main role is the cool/hardcore/funny aspect of the show. Toph is awesome, but I think it'd be weird if she off and got into some relationship. Ya know? People, just leave the relationships alone, be happy with the whole Maiko. Jeez
Zuko's Mother: I too am surprised that so many people have voiced complaints about this. I thought it was an awesome touch, not so much for the imagination of the watchers, but more as a sort of promise that Avatar wasn't going to end there. I don't see them making a whole new series [that'd be lame, since we already saw the finale], but I can see them making a short side story mostly about Zuko [maybe a bit of Aang] and how they find/learn about what happened to Zuko's mother. I personally like some of the theories that have come up in the "Zuko's mother" topic on this forum.
Fanfics/Future Series: I'm personally looking forward to fanfics/future series that AREN'T using the same characters. The finale was quite... final about everything and I think any more episodes about Aang and the rest would just be humor+funny situations. I personally don't want to see anything about Aang's children.