Doesn't this card remind you of something? Well, it sure does remind us of Snapcaster Mage, but this time it's an instant spell instead of a creature. Mission Briefing will be good not only in Surveil-based decks, but in any other blue decks that would like to have more than four copies of Snapcaster Mage.
It's also worth mentioning the Standard format that will lose Torrential Gearhulk after the rotation, which has a similar effect. Mission Briefing is definitely one of the most exciting rare cards in Guilds of Ravnica, which means that the price tag on it will rise significantly as soon as it hits the shelves.