I tested it out last night and it passed with flying colors. With my fairing, I had no worries about the magnets being strong enough to hold it to the tank. I can't say how well they'd do on an unfaired bike. I think if I were using it on an unfaired bike, I would probably want to use the straps or switch-out the magnets for the 4 suction cups which look like they'd be quite strong.
Placement on the tank of course is important since if you place it too close to you, it's harder to look down at the GPS than if you place it forward.
Since the GPS is inside the zippered compartment, you do have to partially unzip it to turn off/on the GPS itself. Luckily, my on/off switch is located at the top-left and the zipper starts on the left so that wasn't a problem. But if your GPS has it's on/off switch in another place, it could be a small hassle.
I had no trouble using the touch screen through the plastic window even with gloves on. The zipper pulls are rubberized and large enough to use with gloves also.