I recommend them. We had one on a previous camper and it saved us from frying our electrical system at a campground one visit. There was something wrong at the power pole, and it kept tripping the surge protector. We had the maintenance man come check it out, and we needed a whole new power pole at our site, which he promptly replaced.
I need to get one for our current camper. I foolishly let the new owners of our previous camper have the other one...