Two things I've really liked about SJA this season-- a stronger Doctor Who connection, and getting to learn more about Sarah Jane. This story is very good at doing both. Now that Luke's met the Doctor (at least via videoscreen) she doesn't have to act all mysterious about him, and dialogue involving the Doctor or the TARDIS just flows more easily.
I especially liked how the Trickster's trap turned out to be a predestination paradox. We don't get much of those in Doctor Who related shows anymore, which is part of what made it work so well.
And man, the Graske is the most used Doctor Who villian who has yet to appear in an actual Doctor Who episode!