It's good a stopping your skin burning but if you want all over skin protection then this stuff should be avoided. Ultrasun (and P20) both filter one type of ray strongly (UVB the one that burns) but lets through much more of the others (UVA+C). The others penetrate your skin deeper. It's these deeper penetrating rays that cause the long term skin damage.
I'm not saying not to use this stuff, just be aware of what it actually does.