It’s consistently good – very very few “bad” episodes, and even those are better than the best of many other shows. The production values are incredible, especially for a show that’s basically about people standing (or walking) around talking. The dialogue is fast and witty as could only be on a show about incredibly smart people.
The second-to-last episode of this season really stood out for me – the way the tension of the main action was played off against the side stories, and underscored (sorry) by the haunting music that ran throughout. Excellent!