I like the actor, but he's totally wrong for the Master. The Master is Roger Delgado or Anthony Ainley, dammit, not some pipsqueak who can't inspire fear in a rodent.
And as for River Song, I'm fine with the actress, but giving the Doctor a love interest flies in the face of like 40 years of canon. That shit's like some holdover from that crappy Fox movie they made where they thought the Doctor had to have a girlfriend to appeal to mainstream audiences. And they wanted her to be Romana part two electric bugaloo where she's the "equal" of the Doctor.

that.
OK, that's enough ultra-nerdery out of me for the day.