Buy the second edition beta ebook here - http://pragprog.com/book/jaerlang2/programming-erlang. The new edition highlights features that are in the yet-to-be-released versions of Erlang. Also has content on how to use tools like rebar.
There's also Chicago Boss, which is a cool web framework. If you are coming from Rails, you'll feel right at home. https://github.com/evanmiller/ChicagoBoss/
The IRC channels: #erlang, #chicagoboss #ninenines (for Cowboy, Ranch, etc) on Freenode.
* No public bug tracker
* epmd's security (or lack thereof)
* Can't insist that epmd be started separately (`erl -no_epmd` won't start epmd but it also won't start epmd's gen_server)
* Can't swap out epmd because while `erl -epmd_module foo` is there, `net_kernel:epmd_module()` is barely used. (Although I don't think it's interface is documented anyway)
* No built-in way to hook UNIX signals
* While the documentation itself is pretty good, it's presentation is lacking and it's difficult to quickly correct mistakes as you run into them
* It can be difficult to reason about when a shared binary will be garbage collected
* OS packaging (I'm thinking of Debian/Ubuntu) of Erlang and Erlang apps tends to be more harmful than helpful (old packages, namespace conflicts, etc)