Stereoscopic viewing of 3D content brings with it a variety of complex perceptual quality issues. For the percept of depth to be convincing, consistent, and comfortable, many parameters throughout the imaging pipeline must to be matched correctly. However, tradeoffs are inevitable for practical reasons, which may lead to various distortions. This paper reviews the issues from an engineering perspective, addressing in particular depth issues, multiview issues, display issues, viewer-specific issues, as well as possible measurements for the overall 3D quality of experience (QoE).