I have been in touch with the Microsoft technical support team many times. Generally it is good, although it depends on the type of support that you have. They have multiple support plans available, and my interaction with them depends on the support that they subscribe to. Some of my clients have premium support plans, in which an engineer will be assigned to you. They track each and every issue and it will be a pretty quick turnaround time for the issues that you face. If you are on a standard support plan then it has its own affiliates that will be followed up by Microsoft. Even in this case, the response time is quite good.
