It's certainly important to know where Erlang doesn't perform so well. Project Euler ( http://projecteuler.net/ ) is also good for exploring the strengths of a given lanaguage. In terms of building robust and scalable distributed systems it cannot be touched. This stems for it's motivating use case of telephony. I'm not sure about Python but I know Haskell has been used largely in academic circles and hasn't had the same amount of attention paid to robustness. Joe Armstrong wrote a very good paper on the history of Erlang's development ( http://lambda-the-ultimate.org/node/2811 ).