I'm one of the true believer of test driven development. To those who are wondering why TDD after all? No, It's not just buzzword, Let me tell you it works, rather It makes your life less miserable! It helps well in many ways.
I'm inspired to jot some recent experiences I'd with an "in-development-legacy" Java Enterprise application, in highly domain centric team (is not fun I know, BA /and not you/ rule that space!), with little focus on code-maintainability because of regular delivery pressure (every software dev. teams I've worked with is not as creative to find outstanding excuse as different than this one, opps that's complex one ;) ).
To come to the point, I just found that if you are new to a *business domain* you might just find TDD one of the most useful technique to ask questions :). You might say WTF? asking questions should be the easiest job on the Earth, ain't it, heh? nah, not always. If you are like me who don't know what to ask (for example situation where there are too many questions to ask about and you are as blank as dry vermouth), Might I advice you to start with a test, because having test will force you to ask dozens of precise questions to start with, apparently you can't continue further development until you get answers for them. Getting answer means you're clear about what's expected of code, the requirements, which means less assumptions and f**k-ups.
Having said that, I've also found when not to TDD, well many would not agree with me but I wouldn't want to judge my code with % of test coverage all the time, which I've found many fanboys in XP-centric organizations do. I mean, come on! Let's not test the obvious code, that's such a waste of time and energy. Well, what I'm not, always, satisfied is lack of time in tddying a lot of complex code just because of less time. The code complexity(cyclomatic or other) is so much so that all permutations will lead me to exponential test counts making it impossible to write tests manually for them (In which case you would love tools like Agitar, if you can afford a license - that is).
Finally, I'm realizing that I'm continuously benefiting from TDD which makes it my favorite technique for development in all environments, what about you?