I know that the iOS version has the "G" pack, but I'm wondering if that G Pack exists for the actual board game or if there are any other expansion packs. Has anyone used those other expansion packs? Are they pretty fun to use? What are some of the cards like?
Yes, the "G" pack exists, as well as the "WM" (World Championship Deck"), France deck, and a few others. The most solid, "balanced" decks IMO are the WM and G decks respectively. They can be purchased online from re-sellers like amazon and such.
They are, however, not in print anymore as far as I know as the Anniversary Collectors edition is due to come out late 2017 with 1000 or so cards that are a combination of all of the current decks in existence, as well as some that are being made to plug in the gaps. That version is going to be for the dedicated type of crowd. There is also a version that just came out with 96 cards that is more of a casual type of crowd.