I especially like some small things like a test folder that is actually named test and the merge of the rake and rails command among some small API changes which could potentially make the start more easy for beginners.
All important libraries that I checked already support Rails 5 so it could be a relatively simple upgrade. I could try to do this if there is no reason against it apart from time.
This page gives a nice summary of new stuff: https://www.sitepoint.com/whats-new-rails-5/
I especially like some small things like a test folder that is actually named test and the merge of the rake and rails command among some small API changes which could potentially make the start more easy for beginners.
All important libraries that I checked already support Rails 5 so it could be a relatively simple upgrade. I could try to do this if there is no reason against it apart from time.