The Garmin Connect Course Editor is a great simple course editor that makes creating new courses very easy, but it does have a couple of issues that Garmin need to sort out.
I'm UK based and set my Edge 500 system settings to English language, British Grid, Statute UK units.
The first issue I have is that I am always being sent the wrong way around roundabouts when I let the Course Editor Follow Roads. In the UK it is customary to go clockwise around a roundabout and taking any other option can lead to some nasty problems, which if you a bicycle based usually means you come off the worse with any vehicle confrontation. OK, I'd obviously not follow a course the wrong way around a roundabout, but with some of the larger roundabouts and intersections, this can make the route distance significantly shorter or longer. This is an irritation as it means a lot of manual editing to get the course right.
The second issue is a real problem though, and one that Garmin need to address to make a good course editor really great. When you create the course the elevation data is very well displayed in feet. When I upload a saved course to my Garmin Edge 500 the elevation data is complete garbage, with vertical ascents of many kilometers and cliff like drop offs of similar proportions. Now I live in a hilly part of the UK, but I know there are no cliffs like this with rounds going straight over them, so I think something must be wring with the elevation data when it is sent (if it is sent) with the course form Garmin Connect to an Edge device.
I've raised a support question with Garmin, but had no response at all - disappointing to say the least.
Other course editing systems I've used in the past, although more cumbersome to create the route, have managed to send elevation data to the Edge, so I know it is possible. Seems a real shame that Garmin can't fix their own good course editor to support elevation data and make this a really great editor.