I did half of last winter with Raceblades. They lack protection on the front of the back wheel, when theres lots of water on the surface, the water goes from the backwheel, splashes on the frame then down your leg, then into your shoes.
They do stop the sprey from the back wheel, and the front(although i never bother with the front one, just have one on the back.
Likes been said protect your frame or it will get scratched.
They are good to take on and off in the summer. I can put mine on and have them on straight in a few mins, which is a bonus when you are going to go out and it just starts raining and you dont want a wet arse.
I have the Giant raceblades, cheaper but just as good. Were abit hard to set up(took them to my LBS to do because i got very annoyed with them)