1) is straightforward, if you don't have enough input buttons you're out of luck. A problem for games like SC2 and WoW.
2) this problem forces you to use acceleration for input, which is commonly accepted to ruin precision (reproducibility) because you lose the easy mapping between inches and pixels.
I'll use Team Fortress 2 (an FPS) as an example for this. First, if 180 degrees takes more than 1 swipe, the controls are effectively unusable. The demonstration indicates this may be the case.
You need to be able to flip 180 degrees to check your back, as well as make other large and fast movements like those required by rocket jumping. At the same time, you also need the ability to make very small aim adjustments. It's guaranteed that the trackpad will be weak somewhere along this variety of movements.
It's unsurprising that it will be a poor replacement for mouse and keyboard, but existing controllers have demonstrated that people are fine with sacrificing resolution of controls for other advantages like relative simplicity and easily playing with friends.