The two decks are gaffed completely differently and they are both quality products. Both are utility props that you could use in many ways. In my opinion they are not all that similar.
I love Unshuffled, but you can't handle it with the same freedom of the Cosmos Deck. For each effect with Unshuffled you need to make a change to the deck. For Cosmos there are many things that you can do without modifying the deck.
Odds are, you will be familiar with the workings of the Cosmos deck when you receive it. Unshuffled uses a method that is a little less common.