Upgrading Drupal should be and can be pretty easy with Composer. However, we currently have two or three packages that need to be updated whenever a new version of Drupal core comes out.

• drupal/core-recommended – Drupal core, itself
• drupal/core-composer-scaffold – Composer scaffolding for required files
• drupal/core-dev – Test and quality dependencies

Using Composer's wildcard abilities, we can get these upgraded in one shot:

composer update "drupal/core*" -W

The -W flag ensures all of the dependencies required by these packages are also updated.