I give this 4.5 🌟. I would give 5 stars for the incredible visually enriching detail that indelibly adds to the veiwer's knowledge of Pandora. The richness of its flora and fauna is simply, breathtaking (especially in 3D). The underlying plot of colonisation, extraction and desecration was not unexpected ,(it is a sequel after all) yet still manages to cause one to empathise with the Navi and Pandora's situation and reflect on our own experiences here on Earth. I find the pseudo-religeous aspect (Eywa) a little irritating but that's just my opinion and hey, its a fictional world, so each to his own.
The aspect of this movie that I do find exasperating (and causes me to drop the rating to 4.5) is the over- anthropomorphism of the Navi personality and family life. For example, the sub-plot relationships between, and reactions of, the various Navi children are so one-dimensional and 'Hollywood' it detracts from the film. There is also unsubtle cultural appropriation such as borrowing from pacific cultures for the Metkayina clan. The familiarity is uneccessary and I definitely do not need Hollywood's cliche version of family life to help me empathise with the Navi and Pandora experience... the main plot (colonisation and Avatar/Navi experiences) and the world James has created is sufficiently rich to do draw me in. I look forward to the next installment.