I don't usually read anything that isn't strictly fantasy, but given this is by Sanderson, I made an exception. I also don't tend to enjoy or go for short stories or novellas because I find that they aren't long enough for me to invest in the story and if I do, it's over too quickly.
Legion is incredibly brief yet incredibly captivating. Sanderson's effortless writing shines through even outside his typical genre in a way that you easily forget you're even reading a book.
The premise, which was a slightly familiar combination of The United States of Tara and Monk was still fresh and cleverly thought out and delivered. We learn that Stephen is a genius, whose mind can do and learn things that we mere mortals can only dream of - however the way he copes with this is by dividing his personality into hallucinatory 'aspects' who each take on and provide him with certain skills and traits, thereby offloading his own mental prowess onto them.
This could so easily present a lot of plot holes, but Sanderson is meticulous and subtle in his handling. While Stephen's aspects make observations and contributions that in fact of course are all derived from Stephen's own experience, there are several moments where it is clear that the aspects are not real and do not have any additional influence in the real world, which I really appreciated.
Within the story Stephen has provided constant intrigue for psychologists and I can see why; I was incredibly interested too. It wasn't so much his prodigious skills, but more the way in which he handles them and the way they manifest themselves - the weapons expert aspect physically guiding Stephen's aim as Stephen's 'own aim' is shaky and terrible for instance.
This worked really well as a short story but I think it could so easily be expanded - like all of Sanderson's other work. I won't push for it though, because I'm still of the belief that we should lock him up until he finishes The Stormlight Archive.