Many times while watching the movie, I've noted the stronger personality of E. Wood being blunted, while the others are having the primary part of the scene. I can barely take my eyes off Elijah Wood when he's doing a scene, because he's just so unusual to look at and his acting is just so strong!
BUT, when there is a scene with someone else, he seems to underact to give the person doing the scene the full glory. An example that I just saw was Sam, Merry and Pippin at the council of Elrond. Frodo has just had this big scene, now it's Billy Boyd's turn. EW's acting is very subtle in that scene. A glance, a small smile. It takes nothing away from Billy Boyd's line. EW has the greater roll, but he takes nothing away from his co-stars by overdoing it in the background.
This just makes me all the more impressed with Elijah Wood's acting.
So...where are we going?