I’m glad you like it Rainer… cos I was just going to suggest (in our little book club thread) whether it might be worth us reading this alongside Programming Erlang 
There’s more maths-orientated stuff I encountered in PE which got me wondering what other Erlang books were out there and whether any might be suitable to read concurrently with Programming Erlang… and Fred’s book has got some really nice reviews! I did similar with Programming Elixir and Elixir in Action and I really enjoyed reading them together (it helps ‘repeat n reinforce’ things too). I’m up for it if you are 
Fred, if you see this, do you have any plans to update this book or do you think it is still good to read with current versions of Erlang/OTP?