I use something similar on my MTB commuter (front and back) and they are working alright for me, given the following:

- I switch between knobbies and Marathons depending on season/conditions and don't want anything that is based on tire width;

- I ride through loads of mud, and occasionally snow, and I like something that is easily unclipped and washed;

- I wear a backpack which keeps splatter off my back and is fairly easy to wipe down.

If you are always riding on pavement and not going through mud or snow, I would recommend full fenders as they do work better.