Indeed it is a potentially good application, but still rough around the edges.

Did you have a play with the 'lead' option? This should fix the problem you have with seeing where you are going better and keeping your 'dot' closer to the lower side of the screen.

Settings -> Auto-Center -> Lead Amount


What I'd love to see is the ability to calculate routing on the N900 itself, unfortunately Google doesn't work for me. I keep getting "Invalid source or destination" - Never once has this feature actually worked.