I don't think I was ever a member of the NUS, since the student union at my university weren't affiliated with it.
Which is why I wasn't surprised by this:
"Tim Berkman, a Bristol University student and member of the Syndicalists, told the Huffington Post UK the NUS was "bureaucratic, and dominated by people who want to get a career in politics rather than change anything" - referring to past NUS presidents such as Jack Straw, Stephen Twigg and Labour MP Jim Murphy."
I never particularly gave a toss about any student union. Most of the people who run them are just using it as a stepping stone into real politics.