during this turn, that monster can attack twice during each Battle Phase, also if that monster attacks, your opponent cannot activate Spells or Traps until the end of the Damage Step
The extra turn does have a mild drawback to it: at the end of that turn, you lose the game
Not all of them have the same symbol, either
Acid-free, PVC-free, and tournament-legal, they slide easily into binders, collector boxes, and deck cases
Possible Future Bans This is more speculation than certainty, but a card is obviously at risk of being banned if it just won its third GP or was central to every Top 8 deck of a pro tour
When players have full transparency on how the system works, it is easier for certain players to exploit this information to create imbalanced match-ups