My experience on SO has been overwhelmingly positive, but I can say that I observe a large difference in the behavior of other users depending on the subject of my question. The C/C++ community is the most pedantic I've experienced, with tons of people jumping in to get those answer points, but also some fussing over question edits, tags, comments, etc. But I don't mind pedantic; they're also the most active, and I don't remember the last time I had a question that was left unanswered.
I've improved my ability to ask focused, clear questions over the years, and that has led to a higher likelihood of getting answers. When I was a student still learning how to code, a lot of my questions would be left hanging, but looking back I think a lot of that was asking unclear questions, or not using the right keywords, or not even understanding what it was I wanted to ask (some was due to asking questions about arcane stuff used only in academia). Overall, I'd say that learning to use SO well has been largely a matter of improving my technical communication skills.
Just wanted to give a word of support for SO. I love that site, I've used it for over 10 years now, and I look forward to having a place to go for technical help for the foreseeable future. It's gold for googling issues, but I can always count on a community there to help me craft another piece of "internet documentation" to help me and the next person.