I'd actually give Wikipedia an 8-8.5 on trustworthiness. Writing quality is another thing entirely.
Lets not delude ourselves. We have a long way to go. I was just looking at some old EB articles the other day; Guerrilla [warfare], written by .......... T. E. Lawrence. And Space-time, written by .......... Albert Einstein.
EB has literally tens of thousands of superb, first rate articles written by the world's leading experts and polished by an editorial staff. Yet we enjoy make fun of a handful of embarrassing errors or shortcomings that have.
Conversely, Wikipedia has literally thens of thousands of piles of festering crap, a huge amount of unverified, uncited information and only a handful of first rate articles. We've been the media's little darling for a long time, not because we are great, but because Wikipedia works _at all_. The media honeymoon won't last forever.
Article validation might help some, but we also need a check valve to keep the good stuff and reject the bad. Experts and great writers aren't going to stick around and watch their work perpetually degraded.
Lest I sound too harsh, remember that the OED, also written with the help of volunteers, took over fifty years to fully publish.