I think it's the fact that you have this previously über-nasty super-villain suddenly showing up in a totally random scene enjoying a cup of vanilla ice cream. LMAO. Future "daddy" Sylar making waffles and acting like a '50s housewife was just as much of an adorable brain-f*ck for the same reason. Ditto with all the cute Sylar/Mr. Muggles (Mrs. Bennet's Pomeranian show dog) moments.
One thing you can say about ZQ is he is now equally famous for playing both a villain and a hero. His appearance does generally favor him for villain roles, but Spock has allowed him to get to be a good guy. And this Spock gets a love interest! It's certainly a step towards leading man roles.
Has anyone heard his Star Trek novelization tape narration? He is REALLY GOOD at doing character voices. His McCoy, the elder Vulcan, Kirk and Nero are all spot on (he sounds exactly like the actors). He even changes his voice for Nimoy-Spock, which was very interesting. It's not that he can't sound like Nimoy, but that he chose to sound like himself. His Chekov sounds like a dead-ringer for Bartok, the albino Russian cartoon bat from Anastasia--which is hysterical, though not particularly Yelchin-like. His Scotty isn't perfect, but it's hilarious. His female voices are just endlessly hilarious (orgasmic Gaila, for instance). He really managed to make scenes both very emotional and funny. But the voices really stand out (which is expected from all the accents like Southern and West Baltimore that he puts on for Heroes).
Here's a few Heroes/Sylar fanvids that I simply adore (he is deliciously evil and then there's dorky mama's boy Gabriel, too!):
http://www.youtube.com/watch?v=DfTDs44-n5c
http://www.youtube.com/watch?v=k4zzxkzcG4Y (speaking of Bartok)
http://www.youtube.com/watch?v=BUbK__T8QZE
http://www.youtube.com/watch?v=rRWz5flRVMU