The Girl in the fireplace was really great (reminded me of Cassanova for obvious reasons but also last season's Fathers Day), and I also loved the Cybermen one and the Satan Pit two parter.
What did people think of the recent love and monsters one with Peter Kay? It was definitely the most different one sofa. Personally I liked it, because it was so fun and different... but probably too much for its own good.
I've noticed that quite a few episodes have music cutting in over the top... Tainted Love...The Lion Sleeps tonight... Bolero... E.L.O... I also think this is a good thing.