I did the coast route early this month - 4 days from Porto Covo to Odeceixe. Spectacularly coloured cliffs and well waymarked throughout. I enjoyed it, and not jus because of excessive amounts of vino verde with dinner each night. Downsides were heat and lots and lots of soft sand, even on top of the cliffs, making hard going.
Inland, on the Historical Way, it'll be hotter but I'd guess that surfaces will mostly be easier.
In any event, I enjoyed it enough to be thinking that, next year, when I must return to Portugal, that I'll likely go back to Odeceixe and push south to Cabo San Vincente.