Yeah, the dialogues and whatnot can always be improved, but the basic gameplay dynamics have to be done well from the start. Scenes like in the blue line when mutants climb down 40 foot walls, jump from one object to the next, switch from running on two legs to all fours, dodge, roll, grab their heads and legs, etc. are about as dynamic as anyone could ask for. With Doom 4 you can expect 30 of them to all come at you at once all doing a variety of different things instead of just running at you like robots and falling over as if their batteries had died.
The wing sticks add a bit of a random element to the mob scenes, but they need more. One thing I loved about Half Life 2 was the addition of objects in the environment flying in all directions and adding a random element to the scenes. You never knew exactly where the stuff would land next or if it would get in your way. In fact, the gravity gun was originally invented just to make sure you didn't get trapped by all the debris and couldn't make it to the next level. It gave the game more replay value and forced people to continue to adapt their strategies. With enough variety in their animations and some random elements added it could make fight scenes really challenging and fun.
I've actually been wondering how id could take their game dynamics to the next level. With the original Doom and Quake games it was all about floor plans, but now its the animations and random elements that are becoming good enough to add some real excitement to corridor shooters.