Selected answers from the Dumb SEO Questions G+ community.
Edward Baker: Approximately only 11 - 12 million websites use it. Having even a few schema designations gives you an unfair advantage simply by elevating yourself to the upper class of websites. It’s NOT a major ranking factor itself but when Google compares two similar sites, rest assured the one with it - even if not entirely correct or complete, will be given a noticeable rank difference. Think of it more as a “guaranteed tie breaker” with lots more upside/potential to be important over time. Search for “free schema generator” or “free schema validator” for help. I am in no way a schema pro, but I too am paying attention to it closely. Technical SEO / Merkle has a generator I see a lot of people use. Hope this helps!
Travis Bailey: Semantic markup mostly helps generate appropriate results, when they`re due, according to Google.
Eddie Nehani: Schema markup helps differentiate your website from other sites who may not be using schema, by telling Google what your pages, FAQ’s, business is about. But schema does not directly impact your rankings. Make sure you use schema as much as possible. Depending on what platform your website is, you can use schema generators, learn it from scratch or use schema markup plugins.