Quality has many dimensions. For a cryptographic library, security is the most important quality attribute and hinges on a good selection of algorithms and the correctness of the algorithm implementations. Yet memory footprint, speed / power consumption and the breadth of supported platforms are also important. These quality attributes are particularly critical for low-cost, battery-powered devices that are the foundation of Massive IoT applications.
Thanks to its quality implementation, ocrypto is the choice of many market-leading companies, for example of Nordic Semiconductor for their Cortex-M4F Bluetooth Low Energy chips.