how would this help otk decks? for every situation this might save you, you'll probably get 2-3 situations where you draw this when you need to draw sundial, dim shield, etc.
More than anything it would let you play mind games with opponent. Suppose you play a big nasty critter that just needs one more round so it can use its ability. You play this to give it time. Opponent otk bolts you on their turn. You then play mirror shield and watch them suck on their own bolt when the delay effect wears off at the end of your turn.
Not saying it isn't situational, but it gives you a way to possibly trick the opponent into acting when they normally would not.
Similar trick could work for "Its a trap" voodoo grav pull, or SoSac.
I.e. you trick your opponent into dealing heavy damage while this is active and turn it against them.
I think it will only be truly useful as a permanent that lasts more than one round though.