I disagree. There is always something to be learned from Stackoverflow. It is impossible that 1 person has the same knowledge of all the users on the site. There are very interesting questions and answers.
Are there allot of simple questions? Yes because there are many people just learning how to do basic things in one language or another. However even in the most basic question answering it can be an worthwhile experience. You can filter out the simple questions and get on to the more advance ones pretty easy.