It's a Marmite type subject, personally I like them and as I've said previously have not ( so far ) managed to get mud on my trousers from the running boards, that's over a period of 27 months and 14000 miles through one of the wettest years I can remember.
Additionally, my wife has had both hips replaced and a serious heel operation in the last 5 years and would find it difficult to get into my car if she didn't stand on the step, she does only have size 4 shoes though.
What I like most about them however is that in conjunction with front and rear mudflaps the volume of much thrown up on to the bodywork is vastly reduced compared to a car without. I have made a direct comparison over identical route as a mate had a GLC without either and we drove the same route to a golf venue.
Like everything, just my personal opinion, we're all different.
That's a good point. MY GLC stays much cleaner than other cars I have owned. I must try and perfect getting out without getting a wet leg ha ha