I tend to agree with Ebert as well, and I've had the same concerns.

I've not been excited by the movie at all leading up to the release. I think a lot has to do with the way it's been marketed to death. You'd think that such an expensive movie wouldn't leave much in the budget for marketing [kidding], but this thing has had way too many tie-ins. The worst I've seen was an episode of Bones a couple weeks ago. Almost the entire episode revolved around Avatar, including a segment where they played practically the entire trailer with the characters watching it during the damn show. That really pissed me off and was enough to get me to skip it entirely.

But now that reviews are coming in, it really does sound like the movie its self is quite good (apparently Zoe Saldana's performance is particularly good, even with all the CG laid on top of her), and the effects might be even better than we were told they'd be.

I'm approaching it this way: there's an Imax 3D theater near me in D.C., and I'll check it out as an amusement park ride. If I so happen to see a good movie while I'm at it, great. Either way I've been told the visual experience is spectacular.

*side note*
I've not experienced this myself, but can anyone speak to the poorer experience one gets at an AMC IMAX? Aziz Ansari's somewhat famous rant really put me off of trying it out (not that there's been much I've wanted to see since then). All I know is that the IMAX website now shows many more IMAX 3D screens in my area than there were before, and the new theaters are ones I've been to, so I know they didn't build new screens in them. I'm with Aziz, I don't want to spend IMAX money if I'm not getting the full IMAX experience. I might spend a buck or two, but not full price...