Amy's sharp. That much is clear in the narrow-eyed way she watches him, clearly thinking, clearly studying him. Besides, the Doctor doesn't tend to take along companions who aren't sharp in their own way, even if it's not necessarily the traditionally academic way.

Amy's scrutiny disappears into a smile at his laugh, though.

Oh, he likes her. He really likes her. But then again, the Doctor's always had pretty good taste. If he does say so himself.

"No. Now, that is impressive. I did kinda wind up clinging to the outside of the TARDIS as we hurtled through the vortex though. Gotta say, not recommended."

Definitely not.

Also, kinda of fatal. To anyone but Jack.