While Thousand-Eyes Restrict is on the field no other monsters can attack, so you'll usually use Instant Fusion in Main Phase 2. From there it can target a monster to take it as an equip, and if it would be destroyed by battle you destroy the equipped monster instead. In other words, you Instant Fusion to steal a monster, and then during the End Phase both cards blow up. While that might seem like an inferior Panzer Dragon, it can take care of some big problems that Panzer Dragon can't.
Thousand-Eyes Restrict gets around two of the hardest monsters to deal with right now: Beatrice, Lady of the Eternal, and Number F0: Utopic Future. Each is phenomenally resilient in the right matchup, and Thousand-Eyes Restrict is an excellent hard counter to both. It's particularly cool in decks like Xyz Monarchs and Kozmos where you can destroy it before the Battle Phase with Kuraz the Light Monarch and Kozmo Dark Destroyer, respectively.
Some players say Thousand-Eyes Restrict is too good to be in the game right now, and others argue that it's not going to affect anything. I think the true answer is somewhere in the middle, where it fills a niche roll as an amazing 1-for-1 removal card, and serves as the next best replacement in your Extra Deck for a second Elder Entity Norden.