I like this card. It's true that Guard Duty with a drawback and higher cost isn't terribly exciting as fas as removal goes, but in certain situations you might get some beneficial damage out of this, and being able to put it on one of your own creatures adds some versatility. It's not very powerful, but I think it's a good option to have in deckbuilding.
I think it's better than Guard Duty with a drawback and a higher mana cost. It's nearly as good as Control Magic with an upside and a lower mana cost.
In a multiplayer game, if you mind control Ulamog, you've got a powerful ally, but the whole table is against you. If you use THIS on Ulamog, you've solved the problem, not gained aggro, AND hit someone else with Ulamog. Yes, Ulamog is still in the way, if I want to hit the player who controls him. That seems like a trivial problem to solve while: a) the rest of the table is dealing with Ulamog, and b) He's not attacking me.
This is a versatile but unexciting card for duels. In multiplayer, this goes on your opponents' guys 99% of the time, and it is unequivocally great. I will play the heck out of this card.