Well, I don't exactly *love* it, but it can be a terrific resource for researching a lot of areas, especially popular culture. There are some topics that other conventional reference sources simply don't cover in that much detail, such as television programs and video games, among *many* others.
Certainly, the fact that anyone can edit the articles means that people with strong viewpoints on specific topics can and do use it as a platform for their agendas (see the Women in Islam article and the Scientology article, for example).
But as I mentioned above, it's a great resource for information on popular culture, as these very well-sourced and well written articles on the Montreal Screwjob incident (an event in professional wrestling in which the World Wrestling Federation defending champion was double crossed and lost his title) and the popular animal drama Meerkat Manor clearly demonstrate.
When using Wikipedia, it's always important to look at the discussion tab to help you assess the quality of the article, even if there are no obvious problems with it.
Avoid any articles with symbols like these in them:
This one shows that the article's neutrality is being assessed.
This one is used to signify a host of problems, including lack of citations or reading like a fan site.
Carleton College's library has created a guide to using Wikipedia that is very informative.