I think you're balls crazy. Square CGI is far cry from Avatar's chime at realism. Square's CGI is more 3D-anime than a try at photorealism and anime style is where they succeed. I don't think the two CGI styles are comparable in any way. Even at a technical level, they both have different goals.
Now I don't know what version you saw, but the Na'vi looked very convincing in 3D and everything else looked freaking awesome too. Better than what I have previously seen and trust me, I love this sort of stuff.
Seriously, saying Avatar's CGI is shit and comparable to 'poor disney graphics' sounds like trolling.
Not to mention when you were talking about FF CGI, if you meant Spirits Within's CGI... Good god man.