Only problem I have with it is that it is internet based and if you do not have an internet connection (like on the road at a hotel which sometimes if iffy even if they say they do have it) then you cannot use it. And even when online I hae found it to be somewhat slow and cumbersome. Even high speed internet connections sometimes are not all that good.
All true! The on the road/hotel part doesn't worry me, as I always have the routes planned in advance and downloaded to my Garmin.
For those that don't know: Although it claims to be just for the US and Canada, it works for most of Europe too (and perhaps other parts of the world). I won't do Poland, Lithuania, Latvia, Estonia, or Russia, unfortunately, even though the road coverage is there, because it refuses to route within these countries. Western Europe is fine though. (HD has a European Rooute Planner too, but it's even worse than MapSource!)
Jim