The best thing about a GPS period is accuracy and data....

http://biffstephens.motionbased.com

The cons for me are battery life and having to take it from your bike and download the stuff....in a few years they will be wireless in some way....

Not having a map is not that bad....personally I like the bread crumb function and it has helped me get home more than a few times....it is still handy....

I like my GPS and I am all for it...and mine take less then 30 seconds to lock on and I can ride while it is doing it...Garmin 305