The real story on UV exposure is total amount. People get sunburnt on beaches because they wear little clothing and spend several hours in direct sunlight. I'm sure if you spent enough time in the sun covered completely in "normal" clothing, you might get a sunburn, but it would take a very long time.
Sure, this clothing will reduce the rate of exposure, but normal clothing does that as well. If you want to protect yourself, cover up, wear hats, avoid direct sunlight when, use sunscreen when you can't. If you're really concerned about daily exposure, invest in a daily lotion that has a SPF. I'm sure a $5 or $10 bottle of lotion will be much more versatile than a $40 hat or shirt.
"A life is like a garden. Perfect moments can be had, but not preserved, except in memory. LLAP"
-RIP Leonard Nimoy