There is circumstantial evidence that he isn't Satoshi, eg, he doesn't sound like Satoshi sounded, he doesn't act in ways congruent with Satoshi's actions, he doesn't seem to share goals with Satoshi's actions, he doesn't seem to have knowledge Satoshi had, etc.

On the other hand, it's absolutely possible that Wright is Satoshi, and is simply engaging in an elaborate hoax in which Satoshi does a great job of pretending to be someone else who is doing a bad job of pretending to be Satoshi. It could be!

This is the bitcoin equivalent of Last Thursdayism (http://rationalwiki.org/wiki/Last_Thursdayism) and much like the original, it's impossible to disprove.

Bottom line though: The real Satoshi could trivially prove he was Satoshi if he wanted to; Wright has not. Either 1) he's not Satoshi, or 2) he doesn't want to prove that he is Satoshi. Given that he spoke to the BBC in an apparent attempt to prove he is Satoshi, we can provisionally rule out option 2, leaving option 1:

He's not Satoshi.