It's an interesting one. To me this is one of the very few episodes that actually manages to pull off the frantic and convoluted style of the Moffat era. At the same time, it also has some of the most annoying and poorly aged early 2010s quirky dialogue that hurts a lot of the 11th doctors run. Somehow makes that almost possible to overlook with it's amazing set and costume designs, cool world building and a truly malevolent feeling villain. Also it has an ood, YAY!!!