Christian has always been someone that's been good as both a face and a heel. In my opinion, he's better than a heel and it's not at all surprising that Christian already has great heat. Everything the WWE has done over the course of the past few weeks with him has been perfectly designed to do just that.
Last week, he hits Randy Orton with the World Heavyweight Championship. Orton is massively over. Whether he's a face or a heel, Orton gets a reaction that's second to none and has for a very long time. As a face, currently, he has fans hanging on his every word and movement. What's a good way of building heat on someone? Have that someone turn on & attack someone that's supremely over at the moment.
Now, Christian initially came out to a somewhat mixed reaction last night. However, virtually all of those cheers he got turned into boos over the course of his promo segment when he insulted the fans. The icing on the cake was asking Michael Cole to come into the ring. Christian talking to Cole as someone to be respected, basically asking him to talk to the fans for him because Christian feels that they're beneath him generally just cemented his heel status. After all, Michael Cole is a walking furnace. The man generates intense heat and Christian got heat just by standing next to him. By the end of the night, Christian attacks Orton again. Not only does he hit him with the belt again, but he causes the very over babyface to lose a big match.
So no, I'm not at all surprised to see how far Christian has come as a heel in such a short amount of time. He has the natural talent & charisma to pull it off. But, that was coupled with the simple fact of being placed into a program & promo segment with the right people.