It's not remotely plausible, but with Willis' McClane leaping onto the tailfins of passing jet fighters and bringing down helicopters by launching police cars at them, there's enough stuff blowing up that action fans won't mind much.
Movie characters like McClane are the Paul Bunyans and John Henrys and Pecos Bills of our age, the stuff of tall tales spun with the technology of an age whose campfires are found in multiplexes with stadium seating.
An enjoyable pop projection of post-9/11 anxiety. That said, it also makes you nostalgic for the days when irresponsible action movies didn't have to deal with it.
Live Free or Die Hard needs a sense of joy, a sense that despite the harrowing nature of the situation, there is something entertaining - even to the participants - about the absurdity of the situation ... it doesn't have that.