We've recently heard and confirmed that the 'Get Started' screen becomes unresponsive for a few seconds on fresh installs on iOS 8.1.
We spent some time trying to figure out what is causing this, we don't have a definitive answer yet, but we'll keep working on it.
What we've found is that if you wait about 5 seconds the button will then become responsive and will get you out of the welcome screen.
We think it is an issue with iOS 8.1. Anyway, we'll submit a fix as soon as we figure it out.
Let us know if this does not work by e-mailing us at firstname.lastname@example.org