A few people on GW2 Guru found some interesting bits on the new demo-build from the gstar-demo. Here whats to expect:
examples so far (standard NPCs):
-) Kiting: enemies kite the player (thanks to Master10k)
-) Dodging: enemies dodge player attacks (thanks to Deity)
-) Weapon swap: enemies swap their weapons to react on your actions (thanks to IsThisNameTaken & Cloudpiercer)
-) Bolt/flee if low on health (various clips)
so these what you would call dynamic fights...
(I tried to link the videos, but because thats my first post I'm not allowed to you find them in the guru forums: