I have never personally used Skinceuticals, but if it's worth anything to anyone, it is one of the brands my dermatologist uses. So, it must do some good.
He also recommends Tizo which I sometimes use as a physical block:
http://solarprotectionformula.com/the_best_solar_protection_products.php

He also recommends Tizo which I sometimes use as a physical block:
http://solarprotectionformula.com/the_best_solar_protection_products.php







). People didn't give a crap about sunscreen in the 80's, my mum fortunately did.
brows
It certainly rocks way more than old La Roche formulas or a bunch of other sunscreens. 
With 5% TiO2 + 5% ZnO it is possible to get up to SPF 30 alone, given that a formula doesn't contain anything that decreases the effectiveness and given that both filters are coated.