First, it let me browse through different spread definitions until I found one I wanted to try, and then it spread the cards for me with my new deck. Just by pointing at different cards, I could read notes about the card itself, and about its position in the spread. Then, with just a few clicks, I was able to look at the very same spread with the *other* deck, and click back and forth between the decks. This not only gave me a different perspective on the spread, but it gave me an excellent way to compare the two decks, letting the similarities and differences between the decks broaden and deepen the meanings for the cards. I could write notes about the reading and save them without having to switch to another program, and I was able to save an image of the cards in their spread for later reference.
What an amazing tool for learning to read the cards. I only wish I could have used it 20 years ago (gulp!) when I was getting started! These young whippersnappers of today have it too easy!

Cheers,
Cowhead