Essentially, it's a collection of magic items, including stats for D&D 5e and Pathfinder. As magic items, they're a good mix. In this starter set, they're all "wondrous items" in the D&D5e sense. That's a plus for me. I tend to prefer wondrous items over +2 whatevers because they nudge the players toward roleplay and story instead of seeing the items only in terms of game mechanics.
On top of being a set of magic items, the described usage is that it's a deck of cards at the gaming table and a deck of cards in the game world. There's a backstory for how the cards came to be and how they might be used in your setting. I considered the old Deck of Many Things arbitrary and silly. The described usage of this Deck of Wonders is only a little less arbitrary, from my perspective. Fortunately, the cards are still usable if you don't deploy the deck as described. Moreover, they don't have to be cards at all, either in-world or at the gaming table. You could use the deck simply to represent unrelated magic items.
A nice touch: "We have purposly desinged [sic] these cards without any names or rules printed on them." This lets you use hand the cards to players while revealing only the info you want to reveal. You can rename them, revise their descriptions, or convert them to another RPG system and still use the cards as handouts.
Speaking of "desinged," the text could use another editing pass in various places.