Shaky cam. Bourne does it well because Paul Greengrass knows there's more to shaky cam than just jerking the camera around. Watch BS and BU closely: notice how each time the camera moves–whether it zooms, or cuts, or jerks–it adds something else to the scene. Every cut introduces some new element that heightens the tension. Greengrass does NOT simply take the scissors and cut his takes up into little bits and paste them together like a collage.

Shaky cam in other films. Often it doesn't work. See "Quantum of Solace." Mark Forster DID simply take the figurative scissors and cut his takes up into little bits and paste them together. He would have been far better off leaving most of the action scene takes as long takes. Take, for example, the opening scene, where the camera zooms in on the tunnel, intercut with Bond shifting gears in his car. The gear shifts should have been ditched, and that camera zoom should have remained ONE SINGLE CUT! It would have been breathtaking if that had been the case. I cannot count the number of times during that film when I wished they had kept one take at one take, instead of splicing it up with other takes. It got to the point where I liked the non-action scenes more, simply for the reason that the camera actually came to a stop and focused on one thing at a time. QOS clearly tried to imitate Bourne in its editing style. It's not the imitation I mind, though; it's the fact that the editors did not understand the underlying techniques and motives that made the Bourne style so popular in the first place.

Don't agree with you sentiment about the Bourne Trilogy, i feel they're some of the more intelligent films to come out of Hollywood in recent years coupled with good action and direction (i like 'shaky cam' but its become a trend to have that feel in films and didn't work for me in Eagle Eye). Its not necessary but to be honest very few films (sequels), if at all any, are ever necessary. If they can deliver on characters and action then it'll be fine, if not, then i'll still have the trilogy. A fourth film won't taint the previous three films or make them better.