Just completed a long distance cycle tour of Holland, Germany and Denmark with this fixed to my handlebars. It rained almost every day, sometimes heavily and for long periods, and never let in a drop of moisture. I followed maps, read/sent texts and emails and listened to music (connected via earpieces plugged in through a waterproof hole in the bottom of the holder) on my iPhone 5.
The extra layer of perspex over the iPhone screen did mean that some of my finger work was not always 100% accurate when typing, but that was only a minor problem.
Good bit of kit.