The high point of this episode definitely was the sub-circuit confrontation with Doyle being blinded in both eyes. I really disliked Doyle's character at the beginning but he has hard not to sympathize with, especially because he has shown great integrity like Jack.
However, many of the plot lines were very predictable. Chloe's pregnancy, though, was definitely unexpected (at least for anyone who didn't read the spoilers) and a more touching CTU mini storyline. A lot of the CTU relationship plots this season have been torturous to watch, so this was refreshing to see.
Another thing that kept this episode afloat was putting Buchanan back into action.
The writers need to fully exploit the abilities of their best actors in the future.