We rode the A397 today. After about 5/6 kilometers the low cloud and visibility was so bad I had to swap to my clear visor. We stopped at the Sale El Madrono, a bikers cafe about half way along that usually has fantastic views for a coffee. We went to Marbella for a couple of hours and then rode back stopping at the same cafe for a bite to eat. The views were a bit better this time. We have to start planning a route back to the ferry tonight.
The verdict from me is that it is probably in the top five best roads I've ridden. I'll mark it down for amount of traffic, some have virtually none and constantly changing speed limits, which I sort of gave up trying to keep track of never mind sticking to.