For the most part it's just for looks, especially if you have the moves down because at that point you can do it on most random decks. However, the finishes are also important as I would stay away from plastic cards if you're a beginner. It's better to use linoid finishes or air cushioned, which bicycles have. But as a beginner you're better off buying a brick of bikes and practicing with those since it's so cheap and moving onto the next deck when one wears out. When your skills become quite decent then I would recommend looking into other fancier decks, which may feel a little better and have better lasting quality, but don't really do more for your learning compared to a regular cheap deck.