Reading about RSpec in The Rails Way, I found this paragraph eloquent:
At first it may seem like the same thing as Test::Unit with some words substituted and shifted around. One of the key points of TDD is that it’s about design rather than testing. This is a lesson that every good TDDer learns through lots of experience. RSpec uses a different vocabulary and style to emphasize that point. It comes with the lesson baked in so that you can attain the greatest benefits of TDD right away. – Obie Fernandez, The Rails Way, p. 625
It reminded me some of my conclusion notes (especially the last sentence), in a very short presentation I gave with a former collegue on Behavior-Driven Development (BDD).