I've been reading wikipedia for years. I enjoy this site immensely. I also, donate money to them. Thanks to all the financial and knowledge contributors who make it happen!
I use it for:
Mathematical and science Reference. I have an MS in Physics.
History study.
Language and cultural reference.
I sometimes use it for computer science reference but, those articles tend to be very unreliable due to a vast culture of unprofessionalism. Computer science academics don't know the difference between a fashionable opinion and a verified fact.