When that was over, I watched DIE HARD 2: DIE HARDER on Blu-ray. Neither of the first two DIE HARDS gained much over their sDVD counterparts on the way to Blu-ray. Starting with DIE HARD WITH A VENGEANCE, however, the differences in the two are night and day.
The Blu-ray did, however, up the ante in the sound department using a DTS-HD MA audio mix that was quite spectacular.