Perhaps we will see him romancing Diane from X factor :-D Unless he is an exceptionally charismatic actor I can't see him making his mark amongst the Whos of history.
I liked him in The Ruby in the smoke, clip of him here (he's Jim) Sadly the only clip I could find shows him having all the 'enigma' of Dick Van Dyke He was marginally better than that..honest.
I think he possibly has the right mix of kookiness and humour for a good Dr (think Tom Baker).And the fact he is little known is a bonus to the part I think. Well we shall wait and see; maybe this will be make or break for the continuance of the series :)