It's good to see that Garmin is supporting the Mac, but they've done a realy bad job. There are some major design flaws with this software (and the hiking counterpart Basecamp).

The biggest flaw is that Garmin decided to store all your routes, tracks and waypoints into one window. Yes you can group them into folders, but since you can't create subfolders, you still end up with a large mess of different types of items into one folder, where there's no distinction between routes, tracks and waypoints beloning to one a route or track. I've set out a 700 km trail and I can't organise it without ending with either tons of folders or a small amout of folders with tons of items. Beside this I do a lot of cycling. I've no idea how to separate this from the trail.
On WIndows MapSource one gdb-file can contain tracks and routes with waypoints from one trip. Waypoints, tracks, and routes are shown separately in one window. You can have several windows open at the same time.
I realy don't see why Garmin made the choice of an app with only one window.

Second, you can draw routes, but you can not extend a route, split a route or join two routes. You can draw waypoints and add them to your route, to extend your route. But this gives you an extra mess (given my point above) So if you draw a route, make sure you finish it completely, before you do anything else, othertwise you have start over again.

On the other hand you can load tracks but you can't draw or alter tracks. Funny enough you can join or split tracks though (and not routes as I pointed out)