Warning: Rebar3 works for me, probably won't work for you yet.
Rebar has been an important tool for many years and many Erlang developers, but for various reasons it has come to show it's age very quickly. The code has become overly complex, especially the transitive dependency management, and became clear to me and a few others that a partial rewrite was required.
The prevalence of rebar
configs in projects meant backwards compatability was a must, however features have been both added and removed.