I agree that he could make an otherwise unbelievable scene believable.
I must admit that I sometimes I've had a hard time telling whether he is joking or being serious. But the more I watch it the more I'm telling the difference between them. Sometimes.
I also like the way he lopes along when running. The Doctor would be striding along then find that the others aren't behind him, lol. Those pesky companions! Always running off or getting lost. Then the Doctor has to risk his neck to get them out of trouble. But many is the time they land up helping him out of a jam, lol. And then how sad for him when the companion leaves.
I always like the scene where Sarah, I think it was her, stayed behind and K9 stayed with his Mistress. Tom went back into the TARDIS and dragged out a box containing a brand new K9. That's a classic scene!
MCH