Gotta agree with Roger Ebert, re: his dislike of 3-D movies.
The extra charge seems is excessive, and I generally have a diminished "movie experience" due to the screen appearing darker and more cluttered (Alice in Wonderland, How to Train Your Dragon). I'd expected tehnology to make 3-D better after all these years, so I tried it again. Bad decision. Alice, in particular, was a visual mess ... the 3-D was less disappointing than the flick itself, but still I wish we'd have chosen the 2-D version.
Worst 3-D for me was Avatar -- oy, pressure headache. Have to admit, though, that 3-D worked for me for Beowulf -- perhaps because of the type of animation it used.