First, the Good: The game is absolutely beautiful. The environments are wonderful... This is why I bought the game. Exploring the world as a Na'Vi is quite fun. I didn't do much as an RDA Human, but it was just as fun.
The Bad: There are many aspects that are grossly lacking in this game. The foremost in my mind is the creatues, as a Na'Vi. First of all, there is no connecting of the queue, you just hop on. As far as I can tell, my Avatar didn't even have a queue (no long hair braid). There was no personal Banshee that you were bonded to, you simply rode them around in special parts of the story that allowed you to.
Worst of all in regards to the creatures, you could not attack from any of them. I expected to be able to fight with my Banshee and also to fire my bow from atop it. But no... Riding any animal in the game completely removes your ability to attack. Which means riding a horse into battle is a sure way to get the horse killed. Same with the Banshee. The "Thanator" has it's own attack which is surprisingly pathetic and often misses, because when it is attacking, it can't also move.
There is no stealth in the game. No sense of sneaking around, stalking RDA. You are either running full speed or walking, but no crouching and moving stealthily. There is a gimmicky invisibility ability, but that does not give the feel of a tactical game, more along the lines of ... oh no, I am about to die, invisibility! Or, I don't want to fight those guys right now, invisibility!
While the environments are beautiful, you feel walled in, heavily walled in. You can only fly so high before you hit a glass ceiling, and in some cases a glass floor. Additionally, flying the Banshee around was alright, but trying to land with it was a total drag. It could only land on perfectly flat large areas. Many a time I had to choose an out of the way, lame landing spot instead of a perfect tactical choice. We really should have been able to shoot bows from the Banshees... without that, there's almost no point in flying them.
There are a few spots where you can get stuck permanently and have to reload, and NPCs will have dialogues with other NPCs even if only one NPC is present, but that's nothing compared to the other issues.
The Ugly: The plot of the game is on par with that of a Uwe Bolle movie, if not worse. You are sent on mission after mission where the goal is exactly the same as the last mission. There is no variety and it gets old incredibly fast. I wasn't even halfway done with the game before I was completely sick of the missions. Go find this guy, fight RDA, talk to this guy, fight RDA, talk to this guy again, fight RDA, get "Shard". Now go to other guy, find a new guy, fight RDA, talk to new guy, fight RDA, go find this guy, fight RDA, talk to this guy, fight RDA, get "Shard". Talk to this guy, fight RDA, find this guy, fight RDA, talk to this guy, fight RDA, get "Shard". Talk to this guy, fight RDA, find this guy, fight RDA, go to this spot, fight RDA, gather "Song". Go back to Hometree, talk to this guy, talk to lady, sing song with lady, talk to lady again, talk to this guy.... and then repeat that three times. (And that was the last half of the game, in it's entirety).
I'll be you were incredibly bored just READING that. Aside from that, your character is a complete imbecile that you never grow to like, ever. You don't even get to create your own character... You select from a few premade characters which probably have the exact same dialogue, story, and name (I have no intentions of slogging through the terrible plot again to see if there is a difference).
I think the final sequence sums up the game very well. A Taruk (big red flying lizard) lands near you, you go over to it... reach your hand out, and voila, you can ride it now. I noted that it only had two eyes, but whatever. You jump on it's back and take flight... woo, it's big, it flies fast, yay. You fly essentially down a tunnel (you can go up a little, down a little, left and right a little, but not much) to an area that looks huge, which is completely walled in invisibly. There is a giant orange beacon for you to land on. You land on it, you walk over to a tree. The end. And that is the first and only time your ride the Taruk, amazing...
...sigh.
At least it's pretty.