The most valuable feature is ease of use.
The documentation is okay.
Download the Identity and Access Management as a Service (IDaaS) (IAMaaS) Buyer's Guide including reviews and more. Updated: July 2022
AWS Directory Service lets you run Microsoft Active Directory (AD) as a managed service. AWS Directory Service for Microsoft Active Directory, also referred to as AWS Managed Microsoft AD, is powered by Windows Server 2012 R2. When you select and launch this directory type, it is created as a highly available pair of domain controllers connected to your virtual private cloud (VPC). The domain controllers run in different Availability Zones in a region of your choice. Host monitoring and recovery, data replication, snapshots, and software updates are automatically configured and managed for you.
AWS Directory Service was previously known as AWS Managed Microsoft AD.