I'll try to give in points a very short overview about Amazon Managed Apache Cassandra Service. This is based on my understanding of available AWS documentations.

Introduction

Amazon Managed Apache Cassandra Service is a managed service provided by AWS that is compatible with Apache Cassandra 3.11 CQL API. CQL is the query language used by Apache Cassandra and is based on SQL.

Apache Cassandra is an open source column store, noSQL, distributed database engine. It was started in Facebook and based on the ideas of Dynamo used in Amazon and Bigtable used in Google.

The service is still in preview and ready for production load yet.

Service type

Serverless; this means you don't manage any servers to use the service.

How the service is accessed

• Being compatible with Apache Cassandra 3.11 CQL API, this allows it to be used by all tools and libraries of Apache Cassandra.
• AWS console provides a web based CQL editor that enables you to run your queries directly from AWS console.

Scalability and performance

• The service auto scale based on the load. No pre-provisioning is needed for throughputs or storage.
• Consistent, single-digit-millisecond response times.

Availability

• Data is replicated 3 times in multiple availability zones within the same AWS region.

Security

• The security model is different than Apache Cassandra; all authentication and authorization is managed by AWS AIM. IAM service-specific credentials are used to access the service end-point.
• The service end-point can be accessed only using SSL encrypted connections. Non-encypted connections are not allowed. So some extra configuration will be required in application level to add AWS certificated.
• Data is encrypted using AES-256 on storage level with encryption keys stored in AWS KMS. There is no option to disable encryption.

Service limitations

• No limits for performance and storage.
• Some CQL queries and data types are not supported. For more details: https://docs.aws.amazon.com/mcs/latest/devguide/cassandra-apis.html
• Also Amazon Managed Apache Cassandra Service doesn't support aggregation functions.
• Quotas: https://docs.aws.amazon.com/mcs/latest/devguide/quotas.html

Pricing

The service is priced based on:

• Read and write requests per request units.
• Storage: based on actual used storage per GB-month.
• Data transfer OUT: the data transferred out of the Amazon Managed Cassandra Service per GB.