Here's a link, to read for yourself: https://www.pokemon.com/us/pokemon-tcg/play-online/bonuses-and-rewards/
And my own synopsis below:
The way it works is this:
7 Wins with a Basic Theme Deck will get you the full deck.
12 wins with any other Theme Deck will get you a pack from the corresponding set.
For each AI character you battle, you will get coins (in increasing amounts) for the first 3 wins and a random pack for the 4th; provided you use a different Theme Deck each time. 1 coin per win thereafter against that opponent, no matter the deck.
For getting all the stars in each league, you'll get 3 random packs all at once. This is in addition to the random bonus pack you normally get for defeating each AI opponent with 4 different decks.
After you get 4 stars from each AI opponent in all 3 Leagues, you are stuck with winning just one coin per win. That's it; forever.
Is it worth it? I personally think that having a free (and easy) opportunity at getting 45 free packs of cards is absolutely worth it; but it depends on your situation. I'm free to play, and have no intention of investing in real cards, so it is a great option for me to take the time to do this.
Have fun out there!
Edited by DrumminBeard, 09 February 2018 - 09:22 PM.