It is a great way for Testers to contribute early in the Sprint as they can start creating all the tests from the beginning.

It increases collaboration between Developers as it requires Pair Programming.

It helps to identify gaps in understanding the desired behavior.

It might lead to better code as refactoring is part of the Test-Driven Development cycle.

It helps break down complex problems into smaller ones that are much easier to be tackled.

It makes Integration Tests obsolete and by doing so saves a lot of time.