Yes, its peculiar situation, though if you see history of US, there have been plenty of such shut downs and by now its no more trending on twitter at our end as #USShutdown as if everything has become normal!
Sufferers are 1 million workers of US who are told to sit at home and wont be paid for days they are sitting, they are sitting at home!

Long term shut down will eat away their sustainability capabilities.
Gainers are US government, saving millions of Dollars without cutting in welfare measures and the corporates who are relieved, they don’t have to bail out government to meet its expenditure, though in any case they were not paying anything extra, but on the contrary government pays them to keep floating by taxying workers!
No effect will be on war effort by US in Afghanistan and Syria!!