If True Strike lasted until you made an attack, I think it would be useful. That way you can cast it out of combat and have your first attack guaranteed advantage. Or, if you want to waste an attack in combat or if you are unable to attack on your turn for any reason, then you could cast it and have advantage of the next attack.
RAW, it's kind of crap. An Eldritch Knight or Bladesinger that can cast a cantrip in addition to attacking may have use of it (though I'd prefer Blade Ward in this scenario), but it otherwise is lackluster in my opinion. It sounds great but it isn't.
Maybe it could be re-written by granting an attack bonus while granting a damage penalty, then the player can opt to have a better chance to hit while doing slightly less damage. +2/-2 maybe? Concentration until broken.
