  The search for physical-layer technologies that can play a key role in
beyond-5G systems has started. One option is reconfigurable intelligent
surfaces (RIS), which can collect wireless signals from a transmitter and
passively beamform them towards the receiver. The technology has exciting
prospects and is quickly gaining traction in the communication community, but
in the current hype we have witnessed how several myths and overstatements are
spreading in the literature. In this article, we take a neutral look at the RIS
technology. We first review the fundamentals and then explain specific features
that can be easily misinterpreted. In particular, we debunk three myths: 1)
Current network technology can only control the transmitter and receiver, not
the environment in between; 2) A better asymptotic array gain is achieved than
with conventional beamforming; 3) The pathloss is the same as with anomalous
mirrors. To inspire further research, we conclude by identifying two critical
questions that must be answered for RIS to become a successful technology: 1)
What is a convincing use case for RIS?; 2) How can we estimate channels and
control an RIS in real time?
