Azure DocumentDB is described as a cloud-powered, globally scaled NoSQL database service that provides high performance with low latency access around the world. It offers millions of requests per second and can store many terabytes of data. Key features highlighted include automatic indexing, easy query capabilities, multi-record transactions, 99.99% SLAs for availability and latency, and globally distributed data replication across multiple regions with configurable consistency models. It is positioned as an alternative to relational databases and other NoSQL options that can better support modern application development needs.