After the announcement of our testing service I asked for feedback from prominent community members. The feedback was overwhelmingly positive with some notable quotes being:

Usability testing of Drupal 7 would have been virtually impossible if it weren't for the automated testing in place keeping core stable.
Brad "beeradb" Bowman

Drupal 7 HEAD is much more stable than any release we [have] ever had.
Károly "chx" Négyesi

It easily saved me a 100 hours knowing I didn't break something I wrote an hour ago. I'm not sure I would have been able to have completed it [DBNTG].
Larry "Crell" Garfield

Testing.drupal.org went live in October 2008, and once again, Drupal's development process was reveolutionized. Now, developers don't need to sit through a test run (which could take 30 minutes or more) in order to verify their changes are working; they can simply upload their changes and be informed by one of the testing clients.
Angie "webchick" Byron

In order to allow Drupal shops to gain the same advantages that Drupal core has received we offer our testing service. Through the service we will maintain an automated testing network similar to testing.drupal.org for use by our clients. In addition we can review your tests to ensure that they are up to standards and provide feedback on ways to improve them.

We are currently working to provide testing of "data sets" which is extremely useful for testing changes against deployed sites. The data from a deployed site can be backed up and tests run against that dataset to ensure that code changes do not break custom workflows or configurations. Testing of data sets does not replace functional testing like that used in Drupal 7 core, but it provides an additional layer of confidence when deploying changes to a live site.