One should use this card over "Royal Decree" in Decks which use Trap Cards frequently. If most of your Deck's other Trap Cards are defensive (i.e. meant to stop an opponent's attack, negate a summon, etc.) this card won't clash with them when used to negate the opponent's Trap Cards during your turn. However unlike the effect of "Royal Decree," which is Continuous and can provide long-term protection, "Trap Stun" only lasts one turn so weigh your options carefully when building your deck.
This card cannot be used to chain a Counter Trap Card, but still can negate it's effect if activated and resolved beforehand. You can use this to disencourage your opponent of activating counter Trap Cards, as they are still vulnerable to other card effects, although they are Spell Speed 3.
If you control a face-up "Splendid Venus", the effects of your Trap Cards will be unaffected by "Trap Stun", though your opponent's Traps will face negation.
This card is a GREAT sucker punch against an Anti-Meta Deck, especially the Tyrant's cards. "Tyrant's Tirade", "Tyrant's Tummyache, "Tyrant's Throes"... all these cards would be useless as soon as you activate Trap Stun, meaning you would be able to use a Monster Effect to destroy these locking Continuous Trap Cards as well.