As weird as this may sound, the problem is Spader. He is so far above and beyond everyone else that everyone else almost looks like has been's. If you think about the rest of the cast and their isolated scenes, they're all pretty evenly matched. But I think for the most part I spend a lot of time anticipating when Spader's next scene is coming along.
So you're blaming Spader for other actors' deficiencies? I'm not sure if it's the writing pandering to Spader's lines, at the expense of the rest of the cast, but the other actors on the show (with exception of the female CIA agent) leave much to be desired. I love Spader, and hope that they can fix these issues, although I'm not entirely confident they can.
Actually, this makes sense to me. I have thought all along that he was so very good, that in comparison (as in next to him in the same scene) all the other actors seem pretty poor. It's a relativity thing. Since she has so many scenes with him, it is very apparent with her--well, and whatever possessed them to put her in that wig hasn't helped at all.