In addition, from the portal, I set up Remote Cron so that Acquia would periodically perform self-maintenance tasks, including caching operations.
A big part of what you're paying for with Acquia Drupal is support; the portal offers a simple way to log support incidents and track your tickets. Depending on your purchase level, Acquia's guaranteed response time can vary from a few hours to the next day. During my testing, Acquia did meet the specified response deadline -- and resolved my questions satisfactorily.
There's also a subscriber forum and documentation. Again, the service was fairly new during my tests, so these areas weren't deeply populated. Still, in scanning the posts from other users, Acquia staff did seem responsive and offered solutions to users' questions.
Time will tell
Although Acquia Drupal was too new to completely evaluate some of the support options (such as discussion forums), the technical underpinnings of this service were solid. Setup and remote management of my Drupal Web site proved to be simple and uneventful. The Ticket Management system worked well. What's more, I believe there are enough subscription levels and support methods (including by phone) for managing production Web sites of many sizes.
As a first version, Acquia has more work to do, too, which company representatives acknowledged. In a briefing, they indicated the staff is looking to integrate more modules, provide better documentation, have simpler deployments (cloud packaging and redistribution through shared hosts), and include more analytics.
Based on a week of testing, I can't offer a meaningful assessment of Acquia's technical support services, nor can I determine whether Acquia will live up to its promise to provide timely updates to Drupal that don't break things. I can say that Acquia makes the deployment of Drupal considerably easier and adds valuable management tools. If the support network follows suit, Acquia Drupal will be a tempting option for organizations that lack the time or staff to deal with the patchwork of a raw Drupal environment.