It seems (from my experiments) that recognition treats all rotations of objects equally. So for instance it recognizes right bracket as left if drawn backwards. I think there should be a caveat warning there. I think it's a neat toy, but frankly I don't understand what attracts GUI designers to gestures. They seem lot more complicated than just buttons (even if you would have to push an extra button to get the menu),…
I like gestures for the same reason I like keyboard shortcuts: you don't have to aim. There's a tradeoff in UIs: large number of targets with few actions, or large number of actions with few targets. An example of the former is a typical web page, where every link is a target and the only actions are open and open-in-tab. An example of the latter is vim, where there are only a couple targets (buffer and command bar) and every key is an action.