I have had this offer on the last 4 cars I have owned, the 3 previous to my Jazz were with Renaults. The 1st one we had came with the Autoglym protection. It was pretty good, and I only needed to clean the car with clean water. The beading of the coating was amazing, and water seemed to slide off the paintwork effortlessly. I was also given an Autoglym care pack with this vehicle. One of the products was Autoglym Aqua wax. After about 6 months, I noticed the beading wasn't as effective, so I waxed the car myself with the Aqua wax (after first giving it a shampoo wash with the Autoglym shampoo suppiled in the pack) Hey presto, back to a really good finish, that repelled dirt and water brilliantly.
I never bothered with the dealer offered protection again, I just waxed it myself and saved myself £300+ each time. Incidentally, I also sprayed my seats with a £10 aerosol of Scotchguard, and that has worked perfectly too. You can get Valetters/Detailers to do this for you, and probably for around the £50 mark.