I've used both the Yamaha one and a Givi Tanklock bag.
The Yamaha uses 2 straps with 'padded' flaps that keep the straps directly off the tank. One strap goes around the headtube, the other around the frame between the seat and fuel tank (in a loop). The tankbag will still move around a bit if you push on it, but it's secured to the bike. The inside liner material is nylon and pretty thin. The zippers are ok quality, but not great. It looks better than the Givi, only because the Givi is larger and sits above the tank. the Yamaha one is around $79 retail.
Both come with rain covers and see thru map pockets on top.
The Givi is easier to use, better quality material and much better zippers. Only the main compartment (though large) and 2 small external side pockets on this model though. It has a GPS holder area in it's map pocket, but doesn't really hold it at an angle you can view while riding. It's about $142 for the bag and $15 for the tankring. This bag never touches the tank.
The Givi is by far, better IMO.
Tanklock System : T480 TANKLOCK LARGE TANKBAG