If you are a Navigon user, I would encourage you not to update to version 2.0 just yet.
I've updated to this new version and am experiencing major problems.
The update installed fine. I was then required to select which map areas I wanted to download. The download took quite some time, and at various stages VoiceOver became unresponsive.
However, it did eventually complete, and I was presented with a button to start the app. On doing so, things immediately went from bad to worse. Although VoiceOver is announcing various page elements, they are not responsive. My iPhone grounds to a virtual standstill, and even flicking between page elements is slow and erratic. When VoiceOver focus in on a button, no amount of double-tapping will make anything happen.
If I had to guess, I would say that running Navigon with VoiceOver simply requires more resources than my iPhone 4 can handle.
I have closed the app and restarted the iPhone. The problem persists. I have disabled VoiceOver, and have enough residual vision to know that the app now appears to work okay.
At the moment I have not heard anybody else report the same problem, but nor have I heard anybody say that it works fine. So, I would strongly entourage people to either delay updating or to be prepared to reinstall the older version.
If you have downloaded the new update, please let us know if you encounter the same issues.