Sarah Shahi and Alan Arkin are back in excellent form as Charlie's very different partners. I'll miss seeing Robin Weigert (Deadwood) if she's truly gone, but I think her replacement as Charlie's boss Donal Logue is probably a good fit. The show, in my opinion, wrestles with the same struggle between light and dark that's going on inside Charlie. Weigert's sad, conflicted character just added to the considerable darkness, wheras Logue's adds to the fun, punching a few more holes in the darkness.
And speaking of the fun, here's a triptych of Sarah Shahi herself...