You can watch Jennifer Aniston go crazy in the latest “Horrible Bosses” sequel, or you can decide to see her in something completely different for a change. I’m not saying you should, but she is definitely the best thing about “Cake”, playing a deeply depressed woman suffering from terrible pain, physical and emotional. Like a train wreck, the movie is surprisingly compelling, and Aniston gives a potent and honest performance (probably the best of her career so far). But the film offers no real pleasure and has no resonance, other than a bitter aftertaste. To say that this is not an easy film to watch is putting it mildly. No one would deny Aniston’s superior performance, but at the end, “Cake” lies there waiting for an animating force that never comes. And that’s a damn shame.