As Ghery posted, it can be useful, but not always accurate. My mother had some 25000+ entries in her records. She claimed that within the commercial programs data can be changed or entered inaccurately, information thereby jumbled. She would only accept "documented" data. How did she get it? The best source is at the Mormon Library in Salt Lake City, and she had been there many times. Other research was done in city halls, town offices, public libraries, personal visits to burial sites pertinent to the ancestry.
Ma used to say that the study of genealogy is a disease, once one gets into it. Also, she claimed to know more about her dead relatives than she did the live ones, and some pretty interesting information would often surface.
When information came from the above sources it was "On Record," not online because somebody wrote it as fact.
HR (who sat through many AZ to ME long telephone dissertations of "You won't believe what I dug up about - - - -."