Wikipedia is as good a source as any. Of course naturally you should cross-reference any
source you use to ensure that the information is accurate and unbiased. If you can find multiple sources stating the same thing, trust it. If you read a Wikipedia article and can't find corroborating evidence anywhere else, you should probably look for a better source.
There are books that are just as full of crud as a bad Wikipedia article, though, so I don't know why people make a big deal of it and claim it's "unreliable" -- then again I don't like generalizations usually.