I generally don't use protective filters, but I was bringing my camera to a couple bars and wanted my front lens element protected in the event of disaster. Attaching this to my nice 50mm f/1.4 was like downgrading it into a substantially cheaper, worse lens. The multi-coating on this filter does almost nothing to reduce flaring, so in anything but broad daylight you'll have plenty of green and pink bubbles zipping around your images. Bright light sources and headlights are a mess of flare, and even with a lens hood I found haze creeping in from off-camera light sources on the side. I'm not a pixel peeper and I'm not the world's foremost expert on image quality, but this filter absolutely wrecked about 60% of the images I took with it.
The one benefit was when I took it off, I felt like I'd just upgraded my lens substantially.
This may be a good option for quickly protecting a cheaper budget lens, but if you own any lenses with nice flare/reflection-reducing coatings, putting this filter on it is basically like scraping the coating off into the trash.