Wikipedia is as good as anything else.
As an example, I frequently use Wikipedia to read about history, computer science topics (e.g. how to implement an algorithm), or scientific topics.
The exception is current events, but even then, I suspect that Wikipedia is not any more biased than the news.
I'm open to having my mind changed, though.
Encyclopedias – including Wikipedia – are not acceptable sources for college-level work certainly. They are tertiary literature, which can provide an overview to someone trying to get a toehold into a subject, and which can hopefully point them toward primary and secondary sources. But tertiary sources are not typically allowable citations for college research.
But, this thread has discussed the reliability of Wikipedia.