"What is the magic trick or incantation to get it to work in general instead of one or two features?"
Hello, I'm sorry that you're unhappy with it. I've found that it takes some exploration within the controls and menus in order to get the hang of which mapsets you need to load up in order to get your desired effect.
It's true that it can spend a lot of time downloading, but I've found that if you avoid the hi-res animations and focus on specific things it can save a lot of time.
A couple of things that may be helpful are the Keychart which you will find under Help, and also the Forums which are available via the link in the page above.
Every time I play with the program I discover new things about it that I had missed before and things that enhance the usability of the program. I would recommend investigating all of the nooks and crannies before completely losing faith in it.....as it's a server-based system rather than an "all in one" like for example the Encarta Reference maps or other atlases that you install as a complete software package, it will be doing some downloading but I've found that after a while you will learn to work with it rather than against it, if that makes any sense (sorry it's late here) :-)
One particularly helpful thing I've found is to become familiar with the Layer Manager and it's subsections....that can help a lot in terms of getting you where you want to go.
Tried to download the "Galileo" sequence and the thing simply hung up on one of the frames. I watched it try to load the same frame about 50 times and get 30% done before I gave up.
I did get some of the other features to work...