I like fenders when its raining. I installed them on my bike and they are great during the crappy weather. But during nice weather I wish they were not on. They do tend to be a tad noisy. I took them off once this summer, but got pelted by the worse rain, thunder and hail storm on the way home. So now I leave the fenders on.

One of my fellow commuters at work hit some dog-doo and didn't have fenders...that's worse than mud! The poor guy was covered in it up his back etc...If that's not reason enough for fenders, I don't know what is. He did go out and buy fenders the next day though and a good headlight...some people don't pick up after their dogs on the paths.