Simply does what it's supposed to do. I particularly like that the Up and Down commands open/close tabs which seems natural to me. With other extensions they are often preconfigured to open/close a window or do other random stuff.

The only thing to criticize is that I do not see an option to edit the threshold of the number of pixels the mouse needs to move in order to initiate a command. (I'd like to set it lower than Foxy Gesture's default setting.)