When I introduce TDD to new people, one of the first question they ask is "how longer does it take?". Dale has a nice post about the real answer to this. To sum up his post the answer is that when taking everything into consideration doing TDD makes development goes faster. this can be backed up by several case studies (found here)
The one thing to add to this is that like any new skill, at start it does take longer. I remember that for me it felt I was going so slowly that in times I thought about forsaking it altogether. (for me the turning point was when I started to feel the power of higher quality but that's another subject) Point is that if you're now evaluating TDD take into consideration a learning curve that will take a few month but at the end doing TDD just make things go faster.