Avatar was a poorly composed 3d experience in my opinion. The combination of depth-of-field effects with stereoscopic vision was really off-putting, I can see shapes nearer to me than the focal point, and can look at them, but can't focus on them.

The only 3d experience I enjoyed - well enough as I wouldn't dissuade someone from viewing the film in 3d, at least - was Gravity, since the small-aperture space cinematography was very suited to a 3d presentation, 3d contributed to the feeling of the film - helping acheive a sense of contrast in scale between the personal experience of the main character and the very large catastrophes around them, and not just a fancy way to produce distractions.