It can be a real money pit detailing. I have seen very large trials testing those ceramic coating products on the detailingworld forum and some were much better than others, the best were from Japan if I remember and very expensive. The worst were no better than regular sealants.
I think most failed to live up to the claims of long term durability but they were not scientific tests or anything.
At least with a detailing company they probably have experience of them and pick the better brands for their customers cars.
On a side note that is a really lovely car and color and worth looking after.