It fails on too many levels. Bad graphics are one thing, but the horrid animations make it lots harder to enjoy.
Story:
Have you seen the series? That's it.
Because the game recreates the series, presumably for people who have already seen it, there are issues like Aang saying "I'm just going to look around and then meet up with Suki.", though he had just met the girl and she hadn't introduced herself, or "It's really nice how everyone has been treating me" though I could only talk to 4 people - and that's not actual dialogue either. It's sloppy and disappointing for those who wanted to experience the Avatar TLA world.
Speaking of dialogue, do we need to be told Appa's lines? As in "growls/yawns" (Yes, that's an exact quote!). Can't we hear him? Is it supposed to be funny? And why can't Aang interact more with Sokka and Katara?
Graphics:
This is a problem before the game actually starts. I expected some nice, preferably new, artwork during the install but what we get is pointless screenshots. How cheap is that? If we install the game we mean to play it, which means we will see Aang bending a lot of times. We can wait 10 minutes for it. And guess what the opening movie is? Oh yeah. The series OP. It's also one of the amazing Extras. At this point I was completely underwhelmed. The first screen I saw made my jaw drop. Not because it looked awesome, but because I saw no Options/Settings to change the resolution. Not seeing any, I clicked on one of the three "New Game" buttons. One had an Air effect, one Water, and one... some crackling sound that stands for Earthbending. How awesome would it have been to be able to play as Toph? But the 3 different games mean just that you can start the game 3 times, and each is autosaved. Once the game started I wasn't expecting great quality, but the graphics are downright awful. This looks too much like an on line Flash game. On top of it, everyone constantly moves in an unrealistic manner. For example, while Zuko talks, he nods his head and clenches his fist in a loop. All the time. It looks horrible. The animation for him turning around lacks any measure of realism or fluidity. His body just spins around like I clicked on "change position". Also, people aren't walking, they are gliding while moving their legs really fast. Aang moves a bit better (a bit!) but despite the fact that his animation suggests running, he advances very, very slowly. Fortunately he can move on his air ball from the very start, which looks more realistic (and is faster).
This isn't just about lack of eye candy, it's really annoying. No one had more than one movement in one scene. If you see Sokka punch the air (I think this is what he was doing...) once, you will see him do it a dozen times, and it's the only thing he does during the entire dialogue - except for standing still, of course. This is extremely unrealistic, and added to the unnatural way this movements are performed, it would have been better if everyone just stood still while they talked. Seriously. Of course Aang keeps turning around (it looks more like dodging huge rocks, but anyway) even while people are talking to him! Not because I don't click on the dialogue screen fast enough, no, WHILE they are talking to him. On the other hand there's some dialogue while Appa is in the air, but Appa doesn't move at all. W00t!
Sound:
After all the "borrowing" from the series, what about the voice acting? Well, that's the good news: it's the voice actors themselves.
The music is also ok.
Gameplay: Fighting is done by clicking the left mouse button on an enemy. It consumes "mana" so you have to keep running around for it to replenish. Unfortunately, you are too slow (when you attack your air scooter disappears!), and because of the lame attempt at graphics and animations it can be hard to realize when the enemies are hitting you. I haven't played that much, but so far fighting is mostly about hit-and-run-way-before-they-come-close techniques being more of a pain than they should be. It's also very boring. As long as you click on an enemy, you hit him, even if the animation shows Aang airbend in a different direction. Plus, once I pushed a firenation guy till he hit another, and the second one didn't move. He only attacked when I moved forward some more.
Katara helped in the battle, but I couldn't see a health bar for her, so I'm not sure what happens when she gets hurt a lot. Frankly, at this point I'm not curious either.
There are also unavoidable mini-games. They are not original, or interesting, or even fun.
Exploring is very restricted (in a more frustrating way than, say, Shadow Hearts, where cities are just a few streets which you explore). Even if there's lots of space behind some trees, you can't go around them, just on the "main street". I couldn't climb on the porches, never mind entering the houses.
People don't walk, don't talk, don't seem to have a life, they just stand somewhere, looking exactly the same, not that there's many of them in the first place.
Conclusion:
Don't buy this even if you are a fan, at least rent it first. For non-fans, don't bother.