Anxiety was pure genius *SPOILERS*
I really have to give credit to their portrayal of Anxiety. As someone who has suffered with anxiety problems in the past, I was initially confused by this strange hyperactive creature - while the other emotions seemed to represent themselves very clearly, Anxiety didn't seem, well, anxious. I expected a character that would be closer to Fear, maybe obsessing over little faux pas, or awkwardly panicking over how they were presenting themselves to the other emotions. Instead, Anxiety seemed more like hyperactivity, zooming around at high speed, extremely smart and gregarious. It confused me.
As the film moved on though, I realised that in actuality I had severely underestimated the filmmakers understanding of anxiety. By the end I was stunned at how perfect the interpretation of a panic attack was - as Anxiety creates a whirlwind of activity in the mind, no other emotion can surface, which is ultimately the true nature of clinical depression (which often comes with anxiety as a kind of 'package deal'). Suddenly, Anxiety's hyperactive personality made sense, because while the other emotions were more obvious in their portrayal, Anxiety was a 'physical' manifestation of an overactive mind, over-analysing everything and creating such a complex web of thoughts that it becomes chaotic and ultimately self-destructive.
Best of all though, was as Joy got to Anxiety - despite the literal whirlwind of activity, Anxiety was actually frozen in place. It's a genius depiction of what's really happening, the torrent of thoughts and feelings moving so fast that it actually stops you from being able to do anything at all. The visual of Anxiety was perfect, everywhere at once but frozen on the spot, tense to the point of rigid, teeth gritted, and also not really there. Trying to focus on a thousand things at once meaning that you're not actually focused on anything at all.
I could go on, but I think I've made my point. While the portrayal of the other emotions is quite blunt and straight-forward, Anxiety was handled differently and with an incredible understanding of mental health issues that I think deserves all the credit in the world.