Sometimes; it depends (like everything else, of course). Links to obviously skewed, biased sites (StormFront
, etc.) hurt an argument.
is an okay resource, but not always. Wikipedia
can be very good for geographic and demographic-style information, e. g. the general census info for Provo, Utah for 2000. Information on celebs (not just entertainment but in fields like medicine) can be spot-on, too. On issues like global warming, it's not so good at all, as the crowd-posting method results in posting wars, and the pages can change on a weekly or even daily basis as people ride their hobby horses and scream at the tops of their lungs. Wikipedia is generally a secondary source at best, but it can be a good way to get to primary sources.
For medical questions, respected sites like WebMD
or sites for places like the Mayo Clinic
are very informative, but they are often interspersed with crap from the latest pretend wannabe Dr. Oz sites (really, if that man wants to have a shred of credibility, then his people need to start suing the acai berry and other quackery sites for using his name without permission. Rachael Ray has the same problem these days).
As for news sites, some are better than others. Breaking news is subject to errors and exaggerations, but that was true before the Internet was a gleam in Al Gore's eye.
As usual, your mileage will vary.