Not bad, but not Opera. Noté 5 sur 5 étoiles
I installed this add-on mostly because I got used to Opera's gestures. It is not intrusive and well designed.
Don't expect, if you're used to Opera's, to perform gestures even on embedded plugins such as flash.
Also, the gestures themselves are subtly different from the ones you'll be used to. They are justifiably better in some ways, so I do not have a strong feeling about it.
Finally, Opera's learning guides are magnificent, but this add-on's alternative, an out-of-the-way tooltip at the bottom, is nearly as good (it shows you the action you'd perform by releasing the mouse, but not those you'd perform by going left, right, etc. from where you are).
Advice: remove that colorful line. It maybe could be discrete and pretty, if it had transparency and antialiasing and was a smooth curve, but mostly it is just ugly and gets in the way.