How do the other branches of Christianity regard Eastern Orthodoxy?

[Virgil]

I believe other posters are right in saying that evangelical and mainline Christian churches don't much think of them at all, and some fundamentalists may project whatever they dislike about the Catholic Church onto the Eastern Orthodox, if they think of them at all. As a Catholic, I can say that Supersoulty is correct in that there are few theological differences between the Catholic and Eastern Orthodox and they are hoping for reconciliation. Also, the Eastern Orthodox is the only other major church (I think the Oriental Orthodox have this, too) that the Roman Catholic Church sees as validly conferring the Sacrament of Holy Orders and all the sacraments associated with it, meaning basically that they believe Confirmation delivered by Eastern Orthodox clergy is just as valid as that delivered by Catholic clergy and that the Eastern Orthodox have transubstantiation. This is why the Eastern Orthodox are one of the few non-Catholic groups allowed to take Communion in the Catholic Church.