COD4 is a quality FPS on t he DS that lacks a little in the control department. Visuals are very nice though.
The whole FPS control system is not what I like about the DS. I understand wanting to use the touch pad, but it's not necessary. I actually had to switch the control system to left handed to get it to work for me. I used my right hand on the touch pad and therefore couldn't touch the right bumper to fire my weapon. To me that is completely backwards and ill concieved. When I reversed it to lefty I was able to use my left hand with the Dpad and the left bumper to fire.
I have also played Goldeneye and really enjoyed that control scheme. It felt like a large console controller, no need for the touch screen.
Where I was please and surprised was the graphics. This is done very well and really makes you feel like you are in the game. This and Brothers in Arms are two of the best looking FPS games on the DS.
Overall I'd say that COD4 is a quality game, but not what I was hoping for when I picked it up. If I had to choose I'd pick BIA over COD4.
Worth picking up at $19.