Yeah, I didn't catch that earlier:

IMO, TDD shines when:

You're doing completely data oriented tests

You're doing things that have to work under changing (non-GUI) conditions without crashing

You're using embedded/system level controllers which need to be functioning under all inputs.

You have a moderately data intensive app and a moderately complex GUI action required to put in edge cases.

You have a automation framework at your disposal to push buttons and capture window contents.

You can structure your project into backend library/front end GUI using library.

TDD lacks luster when:

You have lots of GUIs and no automation framework

You have poor definition of system behavior (proofs of concept based apps sometimes have this)

You have an embedded target with limited debugger support

You have physical switches in your application

You have apps with lots of heterogeneously structured mutli-threading (the more conditionally compiled/run code, the worse the heisenbugs get), especially with a strong GUI component.