It certainly made me think about what I really believe in.
I think Ivan only made Alyosha mad because Alyosha has basically grown up in the monestary, so he's been taught to believe in God & everything that the bible says.
Now Ivan is not so much challenging his beliefs, but presenting another point of view that Alyosha might not have thought about before.
Ivan seems to be more intellectual than was was previously said about him, & I liked that they finally got a chance to talk to one another face to face.