No. Of course not. It is a tool, it’s use can be equally productive for learning as for wasting time. There is a really good article on the Hedgehog Review about this exact issue. The author contends that asking if Google is making us stupider is the wrong question. Instead he argues that we should think of how the technology and the amount of information available is influencing our thought in a more broad sense. Here is an extract:
In order to understand how our lives are already deeply formed by technology, we need to consider information not only in the abstract terms of terrabytes and zettabytes, but also in more cultural terms. How do the technologies that humans form to engage the world come in turn to form us? What do these technologies that are of our own making and irreducible elements of our own being do to us? The analytical task lies in identifying and embracing forms of human agency particular to our digital age, without reducing technology to a mere mechanical extension of the human, to a mere tool. In short, asking whether Google makes us stupid, as some cultural critics recently have, is the wrong question. It assumes sharp distinctions between humans and technology that are no longer, if they ever were, tenable.