Microsofts own study of TDD showed that it definitely improved defect rates and they went fully into developing with it for Vista which is part of the reason for the delays. Nowadays large chunks of the API is automatically tested and this has allowed Microsoft to release changes must more often with a lot less manually testing.

So while this individual is finding his local team isn't getting the full benefits, Microsoft appears to be based on its own report on the technique and its outwards software release cycle changing.