Bravo, let me ask you, if the hero fails his main goal of the story at the end, what is the story about? How is it satisfying? If you were the reader, what would you have thought? I mean, if Marty in BTF hadn't fixed his parents' marriage and gone home, what would be the point of the story?
Or is it like, okay, Harry Potter solves his problem about the Sorcerer's Stone but he didn't really kill You-Know-Who. In that case, it's not quite a cliffhanger -- the book still stands on its own but with an overarching storyline that can be explored in a series; but if the series doesn't take off, it's okay, too.
True, I haven't read your story so I can't really judge if it works or not. Just a question you need to ask yourself, from the perspective of a would-be reader.