The most immediate difference in Quantum of Solace
when compared to most DS games is the fact that it uses the book-style. You turn the DS on its side and use the non-touch screen as a map, while the other screen is where all the over-the-shoulder action happens.
Bond's actions are controlled primarily by a series of gestures made with the stylus, and while this isn't perfect by any means, it does a lot to make you feel like you are really in the action. Controlling Bond becomes a series of taps on the screen to cause him to walk, tapping enemies to shoot or swipes on the screen to use melee attacks. The problem is, there are quite a few times when trying to block (by holding the stylus to the edge of your screen) sometimes gets read as the start of a punch. So instead of blocking, you rear back and get hit. Other times, shooting by tapping on the enemy can cause the camera to change angles, and thus throw off your shots. Again, not good.
Quantum of Solace also features a playing card system to allow you to boost Bond's various stats on the fly. This is an interesting system that will get you different benefits based on how strong of a hand you are carrying.