I voted that they suck, but I am prone to anti-fender hyperbole.

Specific comments: They reduce spray from the bike wheels. Obviously, they do not reduce spray from other vehicles that may or may not pass you by. Thus, depending how many speeding tractor-trailers pass you with a few feet to spare, for example, a third party may have a hard time telling whether you used fenders or not.

I'm not going to suggest that installing something to interrupt the water-jets on your face and back from the tires is a bad idea. The bigger issue is whether FULL fenders are a substantial improvement over clip-ons. For a number of reasons that may not apply to you, I have decided that they aren't.