I LOVED how Aslan was portrayed in LWW (although I do wish they hadn't played with the Deep Magic part, but then again, it's a movie and they don't like to spend a lot of time on explanation)...there were so many great lines, like "I too want my family safe," "Do not cite the Deep Magic to me, Witch. I was there when it was written," "You have to trust me, for this must be done," and of course, the "It is finished" line after Aslan kills the Witch, which a bunch of people recognized as being connected to Christ's last words, (and the connection was completely unintentional on the part of the movie makers).
I WAS, like most people, however, disappointed with Aslan a bit in PC. There should've been WAY more of him. I did love how they still pursued his being ever-present with that huge stone relief of him in the How, and how Peter looks at it in shame when he almost gives in to the Witch (I also love the whole symbolism behind how the Witch was in between Peter, Caspian, and the Aslan carving in that scene--it was like she was standing IN THE WAY, blocking them/cutting them off from the truth, like the hindrance of sin or something). But still, they shouldn't have played with his lines or shortened his actual appearance in the movie.
I'm glad to hear all the rumors that Aslan will be more true to the book in VDT. I sincerely hope they've reverted back to the strong, epic, divine feel that they gave him in the first movie.