This was the ep that cemented Matt Smith as my favourite Doctor since McCoy. Eccleston and Tennant were intentionally less eccentric, less alien and more accessible for The Saturda
I thought about this too while watching this episode. I thought back to Tom Baker saying he would do things that were decidedly un-human since the character is an alien. Smith made me think that with little things he does, tasting the leaf, reacting with disgust at the idea of snogging someone everyone alive would snog, and various other little "alien" actions.
All of that would've been fine and worked better if it were the 3rd Doctor. But the 3rd wasn't befuddled by any of this stuff when he started living on Earth. He wasn't confused about human's, jobs, money, women or courting women. Why should he be? He'd already had at least one child of his own.
So watching 11 mentally revert to someone who act's like they've just arrived on Earth is somewhat annoying at times. Thankfully Smith has the talent to make it bearable, if not funny. However, after interacting with humans for roughly 600 years, and given that 3 wasn't as confused, then the older 11 shouldn't be stumped by a single thing in the area of "humans".