Wikipedia is actually very good, for the most part. There are a few topics that get some abuse, and you need to take those with a grain of salt, but mostly it's just fine.
Unless you are looking for facts, then, it's useless. When people use wikipedia to claim "fact" it tells me that they are too lazy to look up the actual facts. If I were a teacher and a student handed me a research assignment and used wikipedia as a fact source, I'd fail them.
While there may be some accuracy found on wikipedia, it's unreliable enough that NOTHING can be counted on to stand alone as fact if it is from wikipedia alone.