southeastastra - he has a slightly different personality each time, so his dress sense will always be a bit different.
I mean, come on... could be worse...
He looks like the radical and quirky young professor who dresses like the other dons but is far more mischievous and unpredictable. In other words - very Doctorish!
I am surprised, though - I thought they'd go for something more like what he wore in his initial publicity photos, or even something akin to what he wears casually in the street...