There are some reports of people thinking the 3D is darker because of the glasses. I didn't notice this but if you are sensitive to light, this may effect you.
I have to agree. 3D just wasn't worth the extra money. There's nothing special to it. Don't get me wrong, we loved, loved, loved the movie, but I think 2D would have been just fine.
I did notice the colors were a bit muted, also!