So I will admit, I am a huge Bethesda fan and I am just as disappointed as Pete Hines that stuff is getting leaked, but I have peaked at that elusive leaked gameplay video (no story spoilers for me, just gameplay) and I approve very much so. Of course I can't leak anything, but to those who haven't seen it... Wow...
The number one glaring thing I noticed was that it seems, SEEMS, that combat AI has been improved. I saw dumb-dumb Super Mutant hiding in a door frame and peak firing around it to land a few nice hits on the PC. I am not for sure, but based upon the direction of the enemies, I also saw some evidence of flanking.
Now mind you, the PC was absolutely wrecking the mutants, so until we see an 'even' fight, we can't know for sure how AI will accurately react to the PC.
Besides AI I saw solid shooters mechanics, the new loot system (real-time) in action, and a bunch of dead mutants. It was great. I know some other threads have addressed this footage already, but I just wanted to point out the AI and how it reacted.