Quantum metamaterials - controllably quantum coherent artificial media - present a new direction of research at the interface of quantum information processing and physics of artificial electromagnetic materials. They can be thought of as built of qubits, which maintain coherence long enough for the electromagnetic pulse to travel across. The direct access to the quantum state of each constituent "atom" of a quantum metamaterial, together with the global quantum coherence of the system, provide novel opportunities to investigate the foundational questions of quantum-classical transition, a different view of adiabatic quantum computers, and a way to other interesting technological applications. I will review the current state and prospective directions of research in this field, including the possible realizations of quantum metamaterials in the microwave and optical ranges.