The app is for iPhone, that is probably why the window is blurry
Who uses iPhone's anymore anyways? I used one when they first came out for sure, till far better phones with FAR less restrictions came out.
These app's are nice, and I have used a few of them. There are 2 major drawbacks though. First safety glass is double paned glass, therefore the reflection of the phone has a bad ghose effect. Second is that it will only work well when it's dark outside.
The one I use most often is not a HUD app for say.... The phone screen faces you, not the windshield. This one actually watches the road, and can warn you if you veer out of your lane, and even if you are following someone too closely.
Android: iOnRoad Augmented Driving Pro