If the trackpad is any good, and it supports gestures which can be bound, the trackpad has the potential to be as good or better than a mouse. And of course, nothing's stopping you from attaching a mouse to this, meaning the trackpad can now be used for something different. (The fact that it's an LCD trackpad is just screaming for it to be used as a dedicated map viewer/mover in Starcraft.)
Trackpads are surprisingly well suited for FPS. I was with a bunch of programmers recently and we started playing Urban Terror with our Macbook Pros and we did fine with our track pads. It was more difficult to 180 in an instant, but otherwise aiming was almost normal.
Quality is obviously important. A $400 Dell laptop's trackpad would've been awful. Interestingly, a $5 optical mouse is a nearly optimal setup, which is why I doubt there is much attention on trackpads which cost much more.
