I was using Tomtom v3 for a long time (happy). Recently switched to Tomtom v5 (better in some ways, worse in others).
I was thinking of trying Navigon 2005 for two main reasons:
1. Navigon uses Navteq maps, while Tomtom uses the Teleatlas maps. The former are supposedly better.
2. Navigon/Navteq offers more areas than Tomtom/TeleAtlas. Specifically, countries in Eastern Europe and Gulf states (don't care about the latter, though).
If I am lucky enough, somebody is going to jump in and let us all know what Navigon 2005 is like
If not, I may come back to this post in some time to tell you how it went. I should get it for evaluation