Software in the unit is good, just think the PC training stuff is rubbish - much better to put all the info into Triblogs as a training diary!
I've successfully used it to navigate a route, although it does offer some random directions occasionally. Its also way out on estimated calorie consumption compared to my Suunto (at least double!).
If anyone wants to try free maps for it, you could try some open source stuff: http://openstreetmap.org/.
Coverage for smaller roads is no good where I live 'up north', but it might be really good in some areas. Worth looking at if it may save you £60+
As for powertaps, I'd love to try them, but I don't have the budget. Do they work well?