Is Ancestry.com worth the money? Will it help me find the details I need?

I want to research my family tree, but there are a lot of missing pieces that my living family members can't fill in, like great-grandparents' birthdates and birthplaces, and maiden names. I was thinking about getting the World membership to Ancestry.com (about $29/month) to track them down. Is it worth it, and is that the kind of information I'll be able to find there? I want the World membership because I know my maternal great-grandparents immigrated from Germany, but I have no clue where my dad's family is from. I just don't want to spend the money and find out that all I can get is census records. Thanks!