Another thing that sets this film apart is it's theological and metaphysical sophistication. A very good case is made for a second war in heaven. This is because when God bestowed his Grace, his holy spark, unto humans, he raised them up above the angels. Some angels, like Gabriel, just couldn't stand being made second to "a bunch of talking monkeys."
In this sequel, Gabriel returns to earth. This is due to the fact, as Lucifer states early in the film, Hell isn't big enough for both of them. However, this time instead of searching for the one perfect Dark Soul to turn the tide of the heavenly war, he is searching for the new Nephilim, a child of the union of angel and mortal, heaven and earth. Such a being would have the power of an angel combined with the free will and divine spark of a human.
Oh yes, you also get more of the humerous" scenes of Gabriel intercepting the souls of suicides to serve as his helpers. In this case it is a goth girl named Iggy. I don't know why this should be so funny, but it is....
I couldn't think of an actor other than Christopher Walken who could have pulled off this role- who could believable be opposed to the forces of heaven and hell. You actually believe that he would burn down heaven to make his point....
All-in-all, I would say that this is one of those rare sequels that is as good as the original. My only complaint is with the sound levels. Much of the dialog is barely above a whisper. If you boost your sound loud enough to hear it clearly, then you get blasted out of the house by the action sequences.