[nq:1]A mistake I hear English speakers make is "It was so fun," instead of saying "It was so much fun," as if the word 'fun' is an adjective, instead of a noun.[/nq]
?? At least in my dialect, which is close to General American, "fun" is both an adjective and a noun (and, rarely, even a verb), and "It was so fun" is perfectly grammatical.
Jim Heckman