I remember going home for Christmas and my parents paid for my ticket to see this with them in 3D (I hate paying the extra for 3D. Movies are borderline way too expensive anyways). I watched the movie and was blown away by the effects. The flying scenes in particular were very impressive. However by the end of the movie I was already getting bored. I had already gotten over the surprise of the visual beauty and could focus on other things like the characters and plot. Sadly these were ok at best (and that's me being gracious). I came out of the movie impressed with what we could do visually but nothing else.
Then the fans started talking.
I heard things like "best movie of the year" and "revolutionary cinema" and couldn't believ it. There was such an overwhelming amount of praise for things other than the pretty pictures and this made me feel insulted. I love B horror movies. The more over the top and cheesey usually the better. However I would never dream of insulting anyone by insisting that they are good movies. They are fun for me and that's that.
So yes, I probably overreact to people saying they like Avatar. However, whenever someone brings up anything other than the visuals it feels like an insult to my intelligence. I can't speak for others who dislike the movie but I feel like a good number of us would stop caring if the people who do like it owned up to the fact that the graphics are amazing and the rest of the movie is ok at best.