Yes the Peter Kay one was awful and the ones with those silly green farting things in Downing Street (Sounds pretty true to life actually) were pretty poor. Steven Moffat writes the best episodes of the new series, oh and Mark Gatiss.
With the out of place music, well that's the production team trying to be pop-culture, doing the whole Scorsese/Tarantino thing. I hope that by the time Series 5 turns up that Gatiss is the producer, no offense to Russel he's revived the show and revived it well, but he's said himself that the show needs a new air to it.
Change is Doctor Who, and it never comes a moment too soon.