I usually create a trip in Google Maps, convert it via a GPS Visualizer, and then import a .gpx-file to the Everytrail site. On my Iphone app (3GS, Pro version of the app) I get the route that I can then follow.
Since a few weeks (or longer, but I didn't notice it before) I have a very annoying problem: on certain zoom levels the route disappears. I'll try to explain it with two screenshots. The first is on a high zoomlevel, you can see the route highlighted in red. The second one is zoomed in a bit on the same route, but the red line completely disappears.
Everytrail was the perfect app for me, preparing routes on my PC, and then follow them with my iPhone, but now it's almost worthless; detailed junctions etc. are not shown...
I've deleted and reinstalled the app, but this doesn't change anything.