I have spent almost 3 years now writing code(with very few or no tests) and my current organization stresses on agile practices a lot.I encountered TDD from here.So I would like to chip in here too.

TDD solved a major problem for me which I have seen a lot of people suffer with. _Where do I start ?_ . The thing is TDD and refactoring go hand in hand. I cannot imagine doing TDD if I was not using an IDE like Intellij or something. When you normally start writing code first(typical TLD) then you need to have a plan before hand. This plan cannot change much because you really do not get feedback till you complete major segments of the code. TDD ensures you keep getting nibble sized feedbacks which assure you that what you are writing works. This according to me is the single most beneficial point of the system. TDD or TLD would allow maintainable code too.And often while doing TDD too,you can strictly follow TDD. It might not have an impact on code quality for seasoned developers(coding for years on the same codebase) but it does help for the others .It also reduces my inertia considerably too. So while it might not have impacts on development time or code quality. I tend to sleep well without large UML Diagrams floating in my head and knowing that each unit of my code works independently.