For a start, just ignore the GPS part, as for me, this is just a gimmick, promising more than it is capable of delivering.
What it does do is provide a downloadable record of heart rate, speed, distance and elevation at a price cheaper than the equivalent Polar unit.
Software provided is just about useful enough to see what you've done on individual rides but isn't put together well enough to provide a clear and usable summary of your training over a couple of weeks.
One big advantage is you can just put it in your pocket and it records all the data without any kit actually connected to the bike. This is useful if you regularly use different bikes.
The disadvantage of this is you have to remember to bring it with you because unlike your average bike computer it isn't taped to your bike.
And remember to to reset and turn it off when you get in. It doesn't have a time out off feature so if you leave it on the battery will be dry in a couple of hours.
It is possible to sketch out a route on
http://cc2.bradculberson.com/course_creator/cc2
and then upload it to the unit. You can then follow the "breadcrumb trail" on the screen. This takes a bit of time but might be useful on something like a London-Brighton if you were trying out a new route.
There are some other training type "workouts" but it's all a bit convuluted for me.
If anybody knows some xml, apparently Garmin give out the code which downloads the raw data from the unit. This means if you're not happy with their training software you can write your own.
Good luck and if you find out anything else let me know. I'm sure there's people out there who have written all sorts of useful software for it.